SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES ? NUMBER 23
Catalog of Antarctic Meteorites,
1977-1978
Ursula B. Marvin
and Brian Mason
EDITORS
JUL 2 5 1980
SMITHSONIAN INSTITUTION PRESS
City of Washington
1980
ABSTRACT
Marvin, Ursula B., and Brian Mason, editors. Catalog of Antarctic Mete-
orites, 1977-1978. Smithsonian Contributions to the Earth Sciences, number 23, 50
pages, 39 figures, 2 tables, 1980.?During two expeditions to Antarctica
(1976-77 and 1977-78), more than 300 pieces of meteorites were collected
from a small area adjacent to the Allan Hills (77?S, 159?E) in Victoria Land.
The 1977-78 meteorites were collected with special care to avoid contamina-
tion, and were transported in frozen condition to the Johnson Space Center,
Houston, where they were processed under similar conditions to those used for
the lunar samples. Eighty-five specimens of the 1977-78 collection, including
most of those weighing over 100 grams, have been characterized, and are
described in this monograph. Appendices provide a listing of these in numer-
ical sequence and with significant data, and a table of chemical analyses. A
summary of the published data on the ten meteorites of the 1976-77 collection
is also included.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded
in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: Aerial view of
Ulawun Volcano, New Britain.
Library of Congress Cataloging in Publication Data
Main entry under title:
Catalog of Antarctic meteorites, 1977-1978.
(Smithsonian contributions to the earth sciences ; no. 23)
Bibliography: p.
Supt. of Docs, no.: SI 1.26:23
1. Meteorites?Antarctic regions?Catalogs. I. Marvin, Ursula B. II. Mason, Brian
Harold, 1917- III. Series: Smithsonian Institution. Smithsonian contributions to the
earth sciences ; no. 23.
QE1.S227 no. 23 [QB755] 550s [523.5T09989] 80-607055
Contents
Page
EDITORS' INTRODUCTION, by Ursula B. Marvin and Brian Mason 1
FIELD OCCURRENCES AND COLLECTING PROCEDURES, by W.A. Cassidy .. 3
CURATION AND ALLOCATION PROCEDURES, by D.D. Bogard and J.O.
Annexstad 8
METEORITE DESCRIPTIONS, by Trude V.V. King, Roberta Score,
Elizabeth M. Gabel, and Brian Mason 12
TERRESTRIAL AGES, by J.C. Evans and L.A. Rancitelli 45
APPENDIX 1: Characterized Meteorites from the 1977-78 Allan Hills
Collection 47
APPENDIX 2: Chemical Analyses of Some Allan Hills Meteorites 48
LITERATURE CITED 49
in
Catalog of Antarctic Meteorites,
1977-1978
Editors' Introduction
Ursula B. Marvin and Brian Mason
In December 1969, a Japanese expedition
found nine meteorites on a bare-ice area about 5
X 10 km at the southeastern end of the Yamato
Mountains in East Antarctica (near 72?S, 36?E).
Subsequent collecting in this small area resulted
in the recovery of almost 1000 meteorites. Since
the collection included a variety of meteorite
types, this occurrence could not be explained as
the fragmentation of a single large meteorite.
Clearly, some concentrating mechanism had been
operative in the Antarctic, since similar meteorite
concentrations have never been observed else-
where. To test this hypothesis, in mid-1975 W. A.
Cassidy of the University of Pittsburgh proposed
to the National Science Foundation (NSF) a
search for meteorites on the icecap in Victoria
Land, which is accessible from the United States
McMurdo Station. Edward Olsen of the Field
Museum of Natural History in Chicago indepen-
dently planned a similar proposal. As a result, in
1976-77 the NSF Division of Polar Programs
supported a joint expedition by Cassidy and Ol-
sen, which was joined by K. Yanai of the National
Institute of Polar Research, Tokyo. During the
Ursula B. Marvin, Smithsonian Astrophysical Observatory, 60 Garden
Street, Cambridge, Massachusetts 02138. Brian Mason, Department
of Mineral Sciences, National Museum of Natural History, Smithson-
ian Institution, Washington, D. C. 20560.
period 15 December 1976 to 20 January 1977,
this party collected 10 meteorites from the icecap
on the inland side of the Transantarctic Moun-
tains in Victoria Land.
The success of this expedition, which proved
that the Yamato Mountains discovery was not
unique but was likely to be repeated at other
suitable areas on the Antarctic icecap, prompted
extensive discussions among interested scientists
as to the best procedures for exploiting this un-
expected windfall of extraterrestrial material.
Cassidy initiated these discussions at the annual
meeting of the Meteoritical Society in Cam-
bridge, England, in July 1977. In November 1977,
the NSF convened an ad hoc committee of rep-
resentatives from the NSF, the National Aeronau-
tics and Space Administration (NASA), the
Smithsonian Institution (SI), and the scientific
community. As a result of this committee meet-
ing, a plan was drawn up for the collection,
processing, and distribution of Antarctic meteor-
ites collected during the 1977-78 field season.
This plan provided for the meteorites to be col-
lected and returned to the United States, as far
as possible in their pristine condition (in contin-
uously below-freezing temperatures). They were
to be initially stored and processed at the NASA
Johnson Space Center under conditions similar
1
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
to those used for lunar samples. After the com-
mittee meeting, the NSF set up two advisory
groups, the Meteorite Working Group (MWG)
and the Meteorite Steering Group (MSG). The
MWG is composed of approximately ten mem-
bers, representing the field collection teams, the
curation groups, and members of the scientific
community. Its primary responsibility is to con-
sider requests for Antarctic meteorite samples for
scientific research and to prepare an allocation
plan for approval by MSG. The MWG may also
discuss and make recommendations to MSG on
any aspect of the Antarctic meteorite research
program. The MSG is composed of three mem-
bers, one each from NSF, NASA, and SI. Its
function is to review the recommendations of the
MWG, transmit them to the appropriate author-
ities, and to make recommendations on policy
matters.
In order to inform the scientific community as
quickly as possible of the number and character
of the specimens, an Antarctic Meteorite News-
letter with preliminary descriptions of the hand
specimens and thin sections is prepared during
each episode of initial processing. The newsletter
is mailed to interested scientists throughout the
world.
Formal requests for Antarctic meteorite sam-
ples for scientific research should be submitted in
writing to the Secretary, Meteorite Working
Group, Lunar and Planetary Institute, 3303 Nasa
Road 1, Houston, Texas 77058. Requests are
welcome from all qualified U.S. and foreign sci-
entists and are reviewed and considered two or
three times each year by the Meteorite Working
Group. In order for a request to be considered, it
must arrive in the Secretary's office prior to a
deadline published periodically in the newsletter.
Consideration is given to sample requests inde-
pendently of whether or not the requestor is
presently funded for meteorite or lunar samples
studies. It should be noted that sample allocation
does not in any way commit funding agencies to
financing of the proposed research on Antarctic
meteorites. Requests for financial support for re-
search, if required, must be submitted separately
to the appropriate funding agencies.
Sample requests should provide detailed scien-
tific justification of the proposed research. Re-
quests for specific samples should include sample
numbers, weight requirements, and special han-
dling and shipping requirements. Consortium-
type sample requests that are aimed at in-depth
studies of specific samples by groups of scientists
of different specialities are encouraged.
Investigators wishing to study polished thin
sections of Antarctic meteorites in support of their
sample requests can do so at the thin section
libraries, which are established at the Johnson
Space Center (contact Secretary, Meteorite
Working Group), at the National Museum of
Natural History, Smithsonian Institution, Wash-
ington, D.C. (contact Brian Mason, Curator),
and at the National Institute of Polar Research,
Ministry of Education, 1-9-10, Itabashi-ku, To-
kyo, 173, Japan (contact T. Nagata, Director,
and K. Yanai, Curator). These sections are for
optical examination only and cannot be loaned
out. When duplicate thin sections are available,
loans will be considered.
Field Occurrences and Collecting Procedures
W. A. Cassidy
Historical Background
In 1969, a Japanese glaciological team was
establishing a triangulation chain on an ice field
adjacent to the Yamato Mountains in order to
measure local flow in the Antarctic ice sheet.
During this procedure, one of their number, Renji
Naruse, picked up a meteorite. Visual searching
in the area quickly produced eight more speci-
mens, all lying on the ice (Yoshida, et al., 1971),
which were returned to Japan for examination.
In 1973, Makoto and Masako Shima described
four of these specimens at the Meteoritical Society
meeting in Davos, Switzerland (Shima and
Shima, 1973). I attended the meeting out of a
general curiosity about new meteorites and an
interest in the exotic locale in which these had
been discovered. During the oral presentation I
suddenly realized Shima was describing four dis-
tinct subclasses of stony meteorites that had been
found within the remarkably small area of 50
square kilometers. Normally, meteorite specimens
encountered in such concentrations result from a
shower of fragments from the same parent and,
therefore, are all of one subclass; it was startling
to find as many as four types of stony meteorite
reported within such a restricted area.
It seemed necessary to postulate some mecha-
nism of concentration to explain how this could
have occurred. The obvious suggestion, made by
Yoshida et al. (1971), was that the concentration
mechanism has something to do with Antarctic
W. A. Cassidy, Department of Earth and Planetary Sciences, Uni-
versity of Pittsburgh, Pittsburgh, Pennsylvania 15260.
ice: Meteorites falling in Antarctica fall onto a
moving medium and there might be a potential
in this for concentrating specimens from different
falls. Whatever the mechanism, it did not seem
likely that in a continent as large as Antarctica
such an occurrence would be unique.
I discussed these matters with Professor Takesi
Nagata, Director of the National Institute of
Polar Research, Tokyo, during one of his stays as
a visiting professor in our department at the
University of Pittsburgh. As a result of these
discussions, he directed the 1973-74 Japanese
field party to make additional meteorite searches
at the Yamato Mountains site. These produced
twelve additional specimens (Shiraishi, et al.,
1976). Thus encouraged, Japanese field parties
found 663 during austral summer 1974-75
(Yanai, 1976), and 307 in 1975-76 (Matsumoto,
1978). The total Japanese collection as of this
writing, midway through 1979, now numbers an
almost incredible 991 meteorite specimens found
within an area of 300-400 square kilometers at
Yamato Mountains.
My initial proposal to the Division of Polar
Programs, National Science Foundation, submit-
ted in May 1974, was to search for meteorites
during field season 1975-76 on ice patches acces-
sible by helicopter from McMurdo Station. It was
not funded, but I was encouraged to resubmit it
for the following year. In the proposal, I pointed
out the anomalously high concentration of me-
teorites found lying on the ice at the Yamato
Mountains and suggested that other areas on the
Antarctic ice sheet should bear similar numbers
of meteorites. These locations would probably be
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
ones where ablation, or wasting away of the ice
surface, is occurring, while the ice being lost is
constantly being replaced by newer ice arriving
from the interior of the continent.
My proposal was funded for field season 1976?
77. For several years, Japan had enjoyed cooper-
ative research programs with the United States
and New Zealand, working out of McMurdo
Station and Scott Base, respectively, both bases
being located on Ross Island. A joint U.S.-Japan
field search for meteorites in areas accessible by
helicopter from McMurdo Base was established.
It was agreed that all specimens found would be
cut in half and distributed equally between the
United States and Japan. The first year's field
party consisted of Keizo Yanai of the National
Institute for Polar Research, Tokyo, Edward Ol-
sen of the Field Museum of Natural History,
Chicago, and myself.
Yanai had a valuable store of previous Antarc-
tic experience and had been heavily involved in
the Yamato Mountains meteorite recoveries. Ol-
sen had earlier been in Greenland. Therefore, I
was the only member of the group without pre-
vious experience of Arctic or Antarctic conditions.
Our plan was to establish a series of field camps,
beginning with one or two at low elevations under
relatively mild climatic conditions, from which
we could make forays on foot to search for mete-
orites. We planned to work up to more difficult
sites gradually, mainly so that I could become
accustomed to conditions of extreme cold. Our
first campsite, therefore, was at the lower end of
the Wright Upper Glacier, a valley glacier that
carries ice directly off the Antarctic ice plateau.
The glacier is fed principally by ice coming over
the Airdevronsix Icefall, but it also receives a
small increment from a minor ice mass between
Mt. Fleming and Mt. Baldr. The latter site was
our next objective; therefore, I asked the helicop-
ter pilots to take us up there for a fast look
around. As we disembarked on the ice, Yanai
almost immediately found a meteorite (Figure 1).
While we were examining it he was using his
binoculars to good advantage and spotted an-
other one about 700 m away. Olsen, Yanai, and
FIGURE 1.?Meteorite fragment found near Mt. Baldr. Eddy-
current deposit of ice crystals has occurred downwind of the
specimen; wind scooping has occurred at the sides.
I started across the ice toward it while the heli-
copter crew quickly returned to their machine to
follow us aloft. An observer would have been
drawn into the action irresistibly by the sight of
three parka-clad pedestrians crossing the ice, fol-
lowed by a helicopter, all obviously headed for
the same place. We had found two meteorite
specimens essentially in our first twenty minutes
in the field.
We were elated by this initial success, but made
no additional discoveries for about six weeks. We
found no meteorites among the debris at the
bottom end of the Wright Upper Glacier, and
when we set up our next field camp at Mt. Baldr
(Figure 2) we found no more meteorites. Subse-
quently we investigated a number of areas of bare
ice located where the ice plateau meets the
Transantarctic Range, but found nothing. Dur-
ing the closing days of the field season, acting at
the suggestion of Ken Craper, one of the helicop-
ter pilots, we investigated a large patch of ice
adjacent to the Allan Hills. Almost immediately
we found a stony meteorite; then an iron one only
70 meters away. During that visit and another,
several days later, we recovered 45 specimens.
Three were found close together on the ice and
fitted together along fracture surfaces to form an
almost complete fusion-crusted single specimen.
Thirty-three fragments of varying sizes were
found scattered within a radius of 50 meters.
NUMBER 23
These also appear to be fragments of a single
individual; their masses summed to 407 kg. Ac-
counts of these discoveries can also be found in
Cassidy (1977), Cassidy, et al. (1977), Yanai
(1978), and Yanai, et al. (1978).
All our discoveries at the Allan Hills site had
been made using a helicopter as a movable, low-
level observing platform, from which we could
scan large areas in a short time. We found also
that our helicopter pilots quickly gained profi-
ciency not only in spotting rocks from about 10
meters above the ice surface but also in differen-
tiating between rocks and meteorites. Thus we
owe many of these finds and many subsequent
discoveries to the excellent U.S. Navy flight per-
sonnel assigned to support the U.S. research ef-
fort.
The 1976-77 discoveries (Figure 3) demon-
strated that the Yamato occurrence was not
unique; it seemed likely, therefore, that many
more meteorite concentration sites would be
found on Antarctic ice. We suspected from the
beginning that Antarctic meteorites in general
might have unique characteristics not found in
meteorites fallen in other regions. Among these
were long preservation times and low levels of
terrestrial contamination. Further, we felt there
would be good chances of finding rare or previ-
ously undescribed meteorite types and also, pos-
sibly, lunar rocks that had reached the earth as
1 (\
90* W
^SiMC MU RDp STAT
^ ??
YAMATO SITE*
ON",
-_v" #ALLAN HIL
^? ??
"^SYOWA STATION
s}
tS SITE (
FIGURE 2.?Field camp at the Mt. Baldr site. Extra food and
some gear were stowed outside.
FIGURE 3.?Map of Antarctica, indicating the Yamato and
the Allan Hills sites.
products of impact on the moon's surface. Such
musings prompted concerns over the adequacy of
our collecting methods: it would be a shame to
contaminate well-preserved specimens by collect-
ing them in a careless fashion. This concern
prompted me to mail a questionnaire to the
membership of the Meteoritical Society, seeking
an expression of opinion on how Antarctic mete-
orites should be handled. The response (Cassidy,
1979) included both specific and general sugges-
tions which, in sum, outlined a careful curating
process that begins at the moment of discovery
and continues through the transport and later
subdivision of the specimen for research. Based in
large part on these recommendations, the Na-
tional Science Foundation accepted an offer of
help in the curating processing from the National
Aeronautics and Space Administration (NASA).
Currently, therefore, all the meteorite specimens
are sent initially to the NASA/Johnson Space
Center Lunar Curator's Divison for processing.
The National Science Foundation also decided to
eventually house the majority of the U.S. portions
of the collection at the Smithsonian Institution.
During the following field season (1977-78),
our collecting, storage, and transport procedures
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
became much more rigorous. Meteorites were
never touched by hand or gloves, but were picked
up and sealed in teflon bags and kept frozen
throughout the journey from the ice cap to Hous-
ton. My co-investigator for the 1977-78 field
season was Billy Glass of the Geology Depart-
ment, University of Delaware. Keizo Yanai and
Minoru Funaki of the National Institute of Polar
Research comprised the rest of our four-man field
party. We returned to Allan Hills and, collecting
on foot, recovered 309 specimens.
Nature of the Field Occurrence
During field seasons 1976-77 and 1977-78, two
meteorites were found that should be considered
isolated occurrences. These are (1) the two Mt.
Baldr chondrites, which, based on noble gas con-
tent, have now been paired (Weber and Schultz,
1978), and (2) an iron found by a member of a
University of Maine field party, Steven Kite, in
glacial moraine at the seaward end of Victoria
Valley, near Purgatory Peak (Yanai, et al., 1978).
A third, possibly isolated meteorite was found on
bare ice near the upper (southern) end of Man-
haul Glacier only a few kilometers from the main
concentration site at Allan Hills. This specimen
is included tentatively as an isolated occurrence
because the site does not appear to be connected
dynamically to the ice flow and ablation system
that apparently produced the Allen Hills concen-
tration. It was, however, found nearby.
A relatively high frequency of discovery for
isolated meteorites should, I suppose, be expected
in the Antarctic environment because some ice
surfaces may have been in stagnant-flow condi-
tions for very long periods of time and weathering
of rocks proceeds very slowly, so that concentra-
tions could build up over time. The Mt. Baldr
(Cassidy, et al., 1977) and Manhaul Glacier
(Yanai, et al., 1978) occurrences are therefore
understandable as individuals whose survival was
prolonged by fall onto a static surface and by
retardation of the weathering process. The Pur-
gatory Peak occurrence (Yanai, et al., 1978) was
slightly different in that the iron probably was
transported by ice and survived because of the
FIGURE 4.?Area around Allan Hills, Antarctica. Meteorite
concentration was found on the patch of bare ice indicated
by the arrow. (Landsat photograph, spectral band VII.)
slow rate of weathering in the Antarctic environ-
ment.
The Allan Hills concentration is another matter
(Figure 4). Through field season 1977-78 we had
recovered about 350 specimens, representing per-
haps 20 to 50 falls (Yanai, et al., 1978). There is
evidence of ice flowing into the site and wasting
by ablation, which suggests that meteorites found
in the ablation zone could have been transported
over great distances after fall.
The meteorites occur in a zone where ice mov-
ing off the Antarctic Plateau apparently passes
over a rocky ridge, thinning appreciably in the
process. The ice surface along this presumed ridge
forms a monocline whose lower limb is on the
downstream side (Figure 5). Several kilometers
further downstream, the ice meets the absolute
barrier of the Allan Hills. Meteorites were found
on both the upper and lower limbs of the mon-
ocline within an area of about 100 square kilo-
meters. They were relatively more abundant on
NUMBER 23
FIGURE 5.?The Allan Hills meteorite concentration site: a,
View from within the ablation basin (lower limb) looking
toward the slope of the monocline. Ablation has given the
crest of the monocline a hummocky texture; rocks in the
foreground are morainal debris, b, View from the upper limb
of the monocline. Small hill in middle foreground marks the
edge of the upper limb; hills in farther foreground are Allan
Hills; mountain in distance is Mt. Brooks, c, View looking
out over the lower limb of the monocline. Slope leading to
upper limb can be seen beyond; part of Battlements Nunatak
can be seen on the horizon at right of photo.
the lower limb. It seems likely that specimens first
appear on the surface of the ice at the upper limb
and then are carried down to the lower limb,
where they are stored for great lengths of time.
Smaller specimens were often found at the north-
ern border of the ice patch on the lower limb,
where a veneer of snow exists. It may be that
these smaller specimens have been blown across
the ice by the strong katabatic winds coming
from the south and that once they reach snow
their progress stops, so that they are concentrated
along the snow boundary.
The lower limb of the monocline is also pene-
trated here and there by rocky outcrops. These
produce much moraine debris, and meteorites
can be found mixed with this morainal material.
The ice at these points apparently has virtually
zero thickness.
To summarize our field recoveries over two
field seasons, it can be stated that three meteorites
were found that were not parts of high residual
concentrations, and 353 specimens, representing
possibly 20-50 meteorites, were found in one
residual concentration. The sporadic finds seem
to occur in areas of active ablation having no
source of new ice, while the high concentrations
seem to require constant replacement of ablated
ice, as well as active ablation.
Curation and Allocation Procedures
D. D. Bogard andj. 0. Annexstad
Meteorites collected near Allan Hills, Antarc-
tica, in the 1977-1978 field season were packaged
in specially prepared containers and were re-
turned to the Curatorial Facility of the NASA
Johnson Space Center (JSC) at temperatures
below 0?C (Figure 6a). The meteorites were un-
packed, photographed, and processed at the Cur-
atorial Facility by procedures that drew on ex-
perience gained from the processing of lunar sam-
ples. This section describes the return and initial
curation of the 1977-1978 meteorite collection.
The JSC Curatorial Facility supplied the U.S.-
Japanese field party, led by W. A. Cassidy, with
four metal boxes (each about 60 X 60 X 90 cm)
and an assortment of cleaned teflon bags, alumi-
num foil, numbered aluminum tags, and teflon
tape. Two cleaned metal cans with air-tight seals
were also supplied in case particularly rare or
friable meteorites were found. The teflon bags,
aluminum, and cans were cleaned to the same
specifications used in processing lunar samples.
All of these materials were tested in a cold room
at ?23?C before they were sent to McMurdo
Station.
As the meteorites were discovered in the field
they were wrapped in teflon bags, sealed with
tape, and packed into padded metal boxes. Many
of the smaller specimens were packaged several
to a bag, but most of the larger ones were placed
in individual bags. The two carbonaceous chon-
drites were sealed inside the two metal cans.
D. D. Bogard, Geochemistry Branch, Johnson Space Center, Houston,
Texas 77058. J. 0. Annexstad, Curator's Office, Johnson Space
Center, Houston, Texas 77058.
Although an effort was made to keep the mete-
orites at temperatures below freezing, several
specimens were known to have warmed up and
to have contacted liquid water after they were
collected. However, most of the meteorites did
not thaw; snow was still present in fissures in
several specimens. The meteorites were returned
to Port Hueneme, California, in the refrigerated
locker of a ship. Inside a cold room at Port
Hueneme the meteorites were repacked into
metal boxes and dry ice was added. These boxes
were flown air freight to JSC, where the meteor-
ites were unpacked and placed inside a cold
storage room at ?40?C. Ice placed in one of the
boxes in Antarctica was unmelted, which indi-
cates that the meteorites did not thaw after initial
packing.
Initial Processing and Description
Each individual bag, containing one or several
meteorites, was transferred from the cold storage
room to the processing laboratory in the JSC
Curatorial Facility, was placed inside a chilled
stainless steel can on a laminar flow bench, and
was opened. A meteorite was withdrawn and
compared to its field photograph to confirm its
field identification. The meteorite was then
placed inside a clean teflon bag inside a second
chilled can, a processing identification number
was assigned, and the meteorite was returned to
the freezer. This process was repeated for all
specimens. It was possible to identify many me-
teorites with their field photographs and to deter-
NUMBER 23
mine their orientation on the ice. Processing num-
bers initially assigned to the specimens were
30001 to 30307. These were later replaced by the
permanent name/number combinations recom-
mended by the Committee on Nomenclature of
the Meteoritical Society. For all of the 1977-1978
collection, except one meteorite, these carry the
information of locality, Allan Hills (ALH); field
party (A); field season (77); followed by a three-
digit number which identifies each individual
specimen collected. The sequence in which these
last three digits were assigned was based on the
order of unpackaging in Houston, not on the
order of recovery in Antarctica. Thus, when re-
ferred to in the catalog, the first specimen in
the collection bears the identification: ALHA-
77001, XX, where the digits following the comma
refer to subsamples taken from this meteorite
specimen.
The initial processing of meteorites in the Cur-
atorial Facility provided a rapid characterization
of each specimen that was reported to the meteo-
ritical community via the Antarctic Meteorite
Newsletter, which was created for this purpose.
FIGURE 6.?Processing Antarctic meteorites at Johnson Space Center, Houston: a, Arrival of
the metal boxes containing the meteorites packed in dry ice. b, Inside the stainless steel,
controlled-environment cabinets with a nitrogen atmosphere, the meteorites are weighed,
photographed, dried, and chipped, c, Observation port of a processing cabinet, through which
a meteorite is visible on the photo stage, d, Meteorite being chipped inside the processing
cabinet; the chisel and bowl are of stainless steel.
10 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Each meteorite was weighed, photographed, de-
scribed, and a small chip was taken for a thin
section (Figure 6). In most cases the chip was sent
to the Division of Meteorites at the Smithsonian
Institution (SI), where thin sections were made
and the meteorites classified petrographically.
The processing was done in a cleaned, stainless
steel glove box with a controlled nitrogen atmos-
phere, using cleaned tools generally limited to
stainless steel, aluminum, and teflon. The tools
and techniques used were those routinely used for
processing lunar samples, except that techniques
were modified for greater efficiency wherever it
was considered appropriate. The intent was to
prevent any serious contamination or degrada-
tion of the specimens during initial processing.
Attempts were made to keep many meteorites
cold throughout these operations. For example,
photographs were taken while the meteorite lay
on a specially prepared stage, which was kept
chilled by directing a small stream of liquid ni-
trogen onto its underside. The meteorite was
always returned to this cold plate between oper-
ations, such as weighing and chipping. For many
of the larger specimens, a chip was taken to be
kept in long-term cold storage after the main
mass of the specimen had been warmed. A sum-
mary of the initial processing steps in their ap-
proximate order is as follows:
With specimen kept cold, (1) each meteorite
was quickly passed into the processing cabinet,
removed from its bag and placed on a cold plate;
(2) weighed; (3) photographed in color (orthogo-
nals were taken of larger specimens); (4) a chip
was taken for thin sections; (5) a second chip was
taken (from the larger specimens only) for long-
term cold storage; and (6) the specimen was dried
(a few were freeze-dried but most meteorites were
allowed to thaw in the nitrogen cabinet). After
thawing, (7) each specimen was sawed in half and
the cut surfaces photographed and described (Fig-
ure 7); (8) one-half of each meteorite was sent to
Japan along with one of three thin sections made
at the Smithsonian Institution. The two other
thin sections were placed in libraries at the JSC
Curatorial Facility in Houston and at the SI
FIGURE 7.?An Antarctic meteorite being sawed with a band
saw inside a stainless steel cabinet with a nitrogen atmos-
phere; no coolants are used.
Division of Meteorites in Washington, where sci-
entists may examine them.
Pebble-sized meteorites, which generally are
those specimens weighing less than 100 grams
and which were returned several to a collection
bag, were initially processed in a different man-
ner. These meteorites were allowed to thaw over-
night in the processing cabinet, and all processing
operations were done with the specimens at room
temperature. Three specimens at a time from the
same collection bag were processed together.
Only three orthogonal photographs were made of
all three specimens together. No chips for cold
storage were taken from pebbles. Most of the
pebbles were not sawed, but were subdivided by
chipping.
The four iron meteorites in the collection were
handled in yet another manner. The specimens
were allowed to thaw and dry for 48 hours in a
nitrogen cabinet. They were then placed on a
NUMBER 23 11
laminar flow bench, weighed, photographed, and
sealed in a teflon bag. The irons were sent to the
Smithsonian Institution where they were sawed
and subdivided, using the standard procedures of
that institution.
All photography of meteorites was made with
Kodak VPS color film in a large format camera,
which produced 4X5 inch negatives. The six
orthogonal views taken of the larger meteorites
record many details of the surface features (abla-
tion marks, fusion crust, coloration, etc.) as they
appeared before the specimens were divided and
distributed. Photographs also record features on
sawed faces of the meteorites. Generally, the sizes
and shapes of chondrules and clasts, the extent of
internal fracturing, and the degree of oxidation
of the interior metal can be readily discerned in
these color photographs. The lettered cube shown
in the photographs (T, N, E, etc.) indicates rela-
tive orientation of the specimens as assigned dur-
ing processing and does not necessarily indicate
the meteorite's orientation on the Antarctic ice
cap.
Sawing of the stony meteorites in the Curatorial
Facility was done with a cleaned band saw, which
was contained in a nitrogen cabinet and which
was furnished with a diamond-encrusted, stain-
less blade either 0.010 or 0.020 inch thick. Sawing
was done dry; no lubricants were used. Between
specimens, the blade and sample stage was
cleaned and the entire saw cabinet was flushed
with freon to remove meteorite dust. A portion of
the meteorite dust produced during sawing was
swept up, labeled as bandsaw fines, and retained.
The fine dust that was washed from the saw
cabinet was discarded with the freon washings.
Allocations to Scientific Investigators
The meteorites were subdivided according to
guidelines prepared by the Meteorite Working
Group. By prior agreement between the Division
of Polar Programs of the National Science Foun-
dation and the National Institute of Polar Re-
search of Japan, each specimen collected by joint
U.S.-Japanese field parties would be shared
equally between the two nations. Thus, after the
preliminary examinations and descriptions, each
of the larger stones was either cleaved or sawed
in half for division with the Japanese. The U.S.
portion of the specimen was placed in a stainless
steel chipping bowl in a nitrogen-processing cab-
inet. Allocations for requested material were filled
by chipping off appropriate samples with a chisel.
Attempts were made to obtain samples accord-
ing to specific requirements of investigators.
Chipping rather than sawing was used as much
as was practical, to minimize possible contami-
nation. In the case of the achondrites, several
grams of interior material were crushed to provide
representative samples to investigators perform-
ing chemical analyses. In the case of allocations
from carbonaceous chondrites, the final freon
washings of cleaned processing tools were checked
to determine levels of residual hydrocarbons. The
relative positions of the samples were usually
documented. In cases where several samples of
documented subsurface depths were requested
(e.g., for particle track studies), these depths were
either measured when the samples were taken or
a single piece of meteorite containing a wide
range of depths was allocated so that the investi-
gator could extract his own samples. Most pol-
ished thin sections allocated to investigators were
made in the thin-section laboratory of the Cura-
torial Facility. Sections of a given meteorite were
usually made from an interior chip, which was
not the chip from which library thin sections were
made as part of the initial survey.
Meteorite Descriptions
Trade V. V. King, Roberta Score,
Elizabeth M. Gabel, and Brian Mason
This section provides descriptions of the indi-
vidual specimens, arranged by class: chondrites,
achondrites, and irons. Within the chondrites, the
specimens are grouped according to the Van
Schmus-Wood (1967) classification, and the de-
scriptions follow the order of increasing petro-
graphic type. The descriptions are based largely
on those published in the Antarctic Meteorite
Newsletter, with additional information as avail-
able. The letter-number designation for each me-
teorite concurs with guidelines recommended by
the Committee on Nomenclature of the Meteo-
ritical Society; it carries the following informa-
tion: ALH (Allan Hills); A77 (Expedition A,
1977); XXX (digits indicating the number of the
specimen). The original weight of the specimen is
given to the nearest gram (nearest 0.1 gram for
specimens weighing less than 100 grams).
For completeness, the meteorites collected in
the 1976-77 field season (ALHA76001-76009
and Mt. Baldr (MBRA 76001)), described in
detail by Olsen, et al. (1978), and the Purgatory
Peak iron (PGPA77OO6), collected by Steven Kite
of a University of Maine field party in the 1977-
78 field season, have been included.
As mentioned previously (p. 11), half of each
specimen (except for the Purgatory Peak iron) is
preserved at the National Institute of Polar Re-
search, Tokyo, Japan. The remaining material is
held and available for study partly at the Johnson
Trude V. V. King, Roberta Score, and Elizabeth M. Gabel, Northrop-
Houston, Johnson Space Center, Houston, Texas 77058. Brian
Mason, Department of Mineral Sciences, National Museum of Natural
History, Smithsonian Institution, Washington, D. C. 20560.
Space Center Houston, Texas, and partly at the
Smithsonian Institution, Washington, D. C. Each
of these three institutions has a collection of pol-
ished thin sections of the stony meteorites, and
these sections may be examined by interested
scientists.
Preliminary examination of these meteorites
has been based on small chips, usually from near-
surface weathered material probably close to the
fusion crust. In a few instances, more complete
examination and consideration of possible pair-
ings has resulted in a revision of the classification
given in the Antarctic Newsletter. These revisions
are (original classification in parentheses):
ALHA77OO3, H3(L3); 77124, H5(H6); 77191,
H4(H5); 77214, L3(LL3); 77219, mesosiderite
(diogenite); 77224, H4(H5); 77252, L4 with L6
clasts (L5-6); 77278, LL3(L3).
The classification of the meteorites described
here are summarized as follows: CHONDRITES.?
C2: ALHA773O6 (19.9 g). C3: ALHA773O7 (181
g). H3: ALHA77OO3 (780 g), 77299 (261 g). L3:
ALHA77O15 (411 g), 77033 (9.3 g), 77140 (78.6
g), 77160 (70.4 g), 77164 (38.1 g), 77165 (30.5 g),
77167 (611 g), 77214 (2097 g), 77249 (504 g),
77260 (744 g). LL3: ALHA76004 (305 g), 77287
(313 g), 77304 (650 g). H4: ALHA77004 (2230
g), 77190 (387 g), 77191 (642 g), 77192 (845 g),
77208 (1733 g), 77224 (787 g), 77233 (4087 g),
77262 (862 g). L4: ALHA77215 (820 g), 77216
(1470 g), 77230 (2473 g), 77252 (343 g). H5:
ALHA77014 (309 g), 77021 (16.7 g), 77025 (19.4
g), 77061 (12.6 g), 77062 (16.7 g), 77064 (6.5 g),
77071 (10.9 g), 77074 (12.1 g), 77086 (19.4 g),
12
NUMBER 23
77088 (51.2 g), 77102 (12.3 g), 77118 (7.8 g),
77119 (6.4 g), 77124 (4.4 g), 77177 (368 g), 77182
(1109 g), 77264 (11.0 g), 77294 (1351 g), 77300
(235 g). L5: ALHA77OO2 (235 g), 77254 (246 g).
H6: ALHA76006(1137g), 76008 (1150 g), 77144
(7.9 g), 77148 (13.1 g), 77258 (597 g), 77271 (610
g), 77285 (271 g), 77288 (1880 g), MBRA76001
(17881 g). L6: ALHA76001 (20151 g), 76003
(10495 g), 76007 (410 g), 76009 (407000 g), 77001
(252 g), 77150 (58.3 g), 77155 (305 g), 77231
(9270 g), 77261 (412 g), 77269 (1045 g), 77270
(589 g), 77272 (674 g), 77273 (492 g), 77277 (143
g), 77280 (3226 g), 77281 (1231 g), 77282 (4127
g), 77284 (376 g), 77296 (963 g), 77297 (952 g),
77305 (940 g). HP: ALHA77O81 (8.6 g). ACHON-
DKiTES.?Eucrites: ALHA76005 (1425 g), 77302
(236 g). Diogenite: ALHA77256 (676 g). Ureilite:
ALHA77257 (1996 g). Unique: ALHA77005
(483 g). STONY-IRONS.?Mesosiderite: ALHA-
77219 (637 g). IRONS.?ALHA76OO2 (1510 g),
77250 (10555 g), 77255 (765 g), 77263 (1669 g),
77283 (10510 g), 77289 (2186 g), 77290 (3784 g),
PGPA77OO6 (19068 g).
Chondrites
CLASS C2
FIGURE 8
ALHA773O6 (19.9 g).?A fusion crust 0.5-1.0
mm thick is present on approximately 50% of the
13
specimen. The crust is cracked, broken, and fur-
rowed. Some areas are glassy and vesicular; the
remainder of the crust has a dull matte finish.
The specimen is remarkably free of limonite stain.
A light gray weathering rind 2-4 mm deep has
formed on portions of the stone lacking fusion
crust. On freshly broken surfaces the interior
appears charcoal-gray with a slight olive-green
cast. The matrix is fine-grained with 2% to 3% of
light-colored, irregularly shaped inclusions scat-
tered throughout. No obvious chondrules are vis-
ible in the hand specimen, but there are a few
light-colored, 0.1-0.2 mm spherical masses. No
white veins were observed. Several vugs, ~ 1 mm
across, were noted when the meteorite was
chipped in half.
Thin sections reveal a few sparse, poorly de-
fined chondrules up to 0.5 mm in diameter; most
consist largely of granular olivine and some con-
tain small globular grains of nickel-iron. The bulk
of the meteorite (80% to 90%) consists of opaque
to translucent olive-brown matrix, the translucent
material showing weak birefringence; an X-ray
powder photograph shows that the matrix con-
sists largely of a layer-lattice silicate, which by
analogy with other C2 meteorites can be tenta-
tively identified as as ferruginous chlorite. Scat-
tered through the matrix are colorless birefringent
grains, mostly olivine, up to 0.3 mm but usually
FIGURE 8.?ALHA 77306, C2 chondrite: a, A partial coating of fusion crust (lighter gray) is
present, b, Photomicrograph of thin section (width of field is 2.0 mm); irregular grains and rare
chondrules, mainly of olivine (white to light gray) in opaque to translucent matrix (dark gray
to black).
14 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
less than 0.1 mm across. Rare grains of chromite
are present in the matrix. A notable feature is the
apparent absence of metallic sulfides. The mete-
orite is moderately porous, containing irregular
voids up to 0.3 mm across; the specific gravity,
2.58, measured on a small fragment, is therefore
probably somewhat lower than the true value.
No evidence of weathering was seen in the section,
which suggests that the meteorite may be a recent
fall.
CLASS C3
FIGURE 9
ALHA773O7 (181 g).?The rounded specimen
(4.5 X 4.0 X 5.0 cm) is covered with a dull black
fusion crust ~ 1-2 mm thick, except for a fracture
surface at one end (Figure 9a) about ~l/8 of the
total surface area. The fusion crust is character-
ized by delicate polygonal fractures. In a few
places the crust has broken away, revealing a
black fine-grained matrix. The specimen is cut by
several large fracture planes. On the surface near
one of these fractures there is a white material,
which may be an evaporite deposit. The side of
the specimen that was in contact with the ice at
the time of recovery is slightly reddish. Small,
irregular white inclusions and several chondrules
are apparent on some freshly broken surfaces.
The thin section (Figure 9b) shows a closely
packed aggregate of mineral grains (up to 0.2
mm), mineral aggregates (up to 0.8 mm), and
rather sparse small (0.1-0.5 mm) chondrules, set
in a dark brown to black opaque matrix; the
matrix makes up to 40% to 50% of the section.
The mineral grains, aggregates, and chondrules
consist of olivine and polysynthetically twinned
clinopyroxene in approximately equal amounts.
Microprobe analyses show that most of the olivine
has forsterite composition, Fa~i, with a few grains
ranging up to Fa3o; the average for 30 grains is
Fas. The pyroxene is mostly clinoenstatite, Fs~i,
but with a few more iron-rich grains. A little (1%
to 2%) nickel-iron is present in the matrix as
scattered grains, many partly altered to brown
limonite. Fine-grained sulfide (~5%) is dispersed
throughout the matrix. Fusion crust, 0.5 mm
thick, is present along one edge of the thin section.
The meteorite is a carbonaceous chondrite; an X-
ray powder photograph shows that the matrix
consists largely of olivine and pyroxene with some
magnetite, which indicates a C3 classification.
CLASS H3
FIGURE 10
ALHA77OO3 (780 g).? The specimen (Figure
10a) is very well-rounded and no surface fissures
FIGURE 9.?ALHA773O7, G3 chondrite: a, Fusion crust is crazed and broken away in places, b,
Photomicrograph of thin section (width of field is 2.0 mm); irregular grains, aggregates, and
rare chondrules of olivine and pyroxene (white or light gray) in dark brown to opaque matrix
(black).
NUMBER 23 15
FIGURE 10.?H3 chondrites: a, ALHA77OO3, upper surface, showing fusion crust, b, ALHA
77299, photomicrograph of thin section (width of field is 2.0 mm); a closely packed mass of
chondrules and irregular aggregates mainly of olivine and pyroxene set in a minor amount of
dark matrix.
are present. A medium black, slightly glassy fu-
sion crust, 1-3 mm thick, covers approximately
35% of the meteorite on the surfaces that were up
at the time of discovery. The remaining surface
of the meteorite is smooth, brownish black, and
has a polished appearance, which may be due to
wind action or to the presence of the lower portion
of an abraded fusion crust. There is very little
iron-oxide staining, except on one area of approx-
imately 1X2 cm where the interior is exposed.
Abundant small (~1 mm) metallic flecks, chon-
drules, and lithic clasts were observed after the
meteorite was cut in half. These inclusions, with
the exception of the metallic material, for the
most part ranged in color from white to tan. The
overall dimensions of the stone are 10.3 X 8.7 X
9.2 cm.
The polished thin section shows numerous and
well-defined chondrules, 0.1-0.6 mm in diameter,
together with mineral clasts, in a fine-grained
groundmass, which is stained brown with hydrous
iron oxides. The chondrules exhibit a variety of
form and structure, the most common consisting
of granular aggregates of olivine and polysyn-
thetically twinned clinopyroxene; some chon-
drules have pale brown transparent glass intersti-
tial to the olivine and pyroxene grains. Micro-
probe analyses show that both olivine and pyrox-
ene have a wide range of composition. Olivine
ranges from Fa4 to Fa48, with a mean of Fa22;
pyroxene ranges from Fs2 to FS25 with a mean of
Fsi4, and its calcium content averages 1% CaO.
The wide range of composition of olivine and
pyroxene indicates a type 3 chondrite, and the
chemical analysis (Appendix 2) shows that it
belongs to the H group (this meteorite was ten-
tatively classified L3 in the preliminary exami-
nation) .
ALHA77299 (261 g).?The specimen (9.5 X
5.5 X 3.5 cm) is roughly tabular. A thin patchy
fusion crust covers approximately 10% to 15% of
the surface. The remaining surface areas are
smooth, medium brown, and partially coated
with glass, which probably is the inner portion of
an abraded fusion crust. Fresh metal, chondrules,
and lithic clasts are visible in hand specimen. A
weathering rind, 1 mm thick, is present on all
sides of the specimen.
The thin section (Figure 10b) shows a closely
packed mass of chondrules (0.15-1.5 mm diame-
ter) and irregular crystalline aggregates with in-
terstitial nickel-iron and troilite and a small
amount of matrix. A considerable variety of chon-
drules is present: many are granular or porphyr-
16 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
itic olivine with transparent to turbid interstitial
glass; other types consist of fine-grained pyroxene,
medium-grained olivine and polysynthetically
twinned clinopyroxene, or barred olivine. The
section is stained yellow-brown with limonitic
material, with small areas (as much as 0.4 mm
across) of reddish brown limonite along one edge
(near-surface?). Microprobe analyses show olivine
ranging in composition from Fan to Fa2i, with a
mean of Fai6; the pyroxene is low-calcium (CaO
= 0.4% to 1.2%), with a range in composition
from Fsis to FS20 and a mean of Fsi8. The mean
composition of the olivine and the amount of
nickel-iron suggest H group, so the meteorite is
classified as H3. A chemical analysis of this me-
teorite is given in Appendix 2.
CLASS L3
FIGURES 11-15
ALHA77O15 (411 g).?The specimen (Figure
1 la) is angular, 9.0 X 5.5 X 5.0 cm, and charcoal-
brown fusion crust with vitreous luster covers
approximately 50% of the surface. Fusion crust is
present on the S surface, and is partially preserved
on the B surface. The remainder of the sample is
devoid of fusion crust; however, it is nearly the
same color as the portion with fusion crust. Both
angular lithic fragments and chondrules are ob-
served on the B surface. These range in color from
light brown to dark gray and are as large as 0.5
cm in maximum length. Many fractures are pres-
ent. When the meteorite was cleaved it broke
along fractures, thus producing only one chip
with unweathered material exposed. This chip
revealed dark matrix with small, unweathered
metallic grains.
The polished thin section shows a closely
packed aggregate of chondrules, 0.2-1.8 mm in
diameter, with only minor fine-grained matrix.
Chondrules are mostly olivine and olivine plus
polysynthetically twinned clinopyroxene; trans-
parent pale brown glass is interstitial to olivine
and pyroxene grains in some chondrules. Minor
subequal amounts of nickel-iron and troilite are
present, concentrated in the matrix and at chon-
drule margins; the nickel-iron grains are corroded
extensively and altered to limonite, and thin veins
of limonite occur throughout the section. Micro-
probe analyses show a wide range in the compo-
sition of olivine (Fai-Fa2i) and pyroxene (Fs4-
FS24); the pyroxene is a low-calcium clinopyrox-
ene (CaO = 0.2% to 0.5%). This range of com-
4*V ? *
FIGURE 11.?L3 chondrites: a, ALHA77O15, part on the right is coated with fusion crust; the
part on the left is a fracture surface, b, ALHA77O33, photomicrograph of thin section (width of
field is 2.0 mm); a close-packed aggregate of chondrules characteristic of type 3 chondrites.
NUMBER 23 17
FIGURE 12.?L3 chondrites: a, ALHA77140, photomicrograph of thin section (width of field is
2.0 mm); chondritic material encloses a granular nonchondritic enclave, b, ALHA7716O,
photomicrograph of thin section (width of field is 2.0 mm); a close-packed aggregate of
chondrules characteristic of type 3 chondrites.
position, together with the presence of glass and
twinned clinopyroxene, indicates type 3, and the
small amount of nickel-iron suggests L group; the
meteorite is therefore tentatively classed as an L3
chondrite.
ALHA77033 (9.3 g).?The specimen is angu-
lar, rough and dark brown. Exterior surfaces are
highly weathered and do not appear to have
fusion crust. The stone chipped easily, revealing
a highly oxidized broken face.
The polished thin section (Figure 116) shows a
closely packed mass of chondrules (0.3-1.1 mm
diameter) and irregular crystalline aggregates,
with a small amount of interstitial nickel-iron and
troilite (1% to 2% of each) and a relatively small
amount of fine-grained matrix. A considerable
variety of chondrules is present, the most common
being granular olivine and olivine plus polysyn-
thetically twinned clinopyroxene, porphyritic ol-
ivine, and fine-grained pyroxene. Some chon-
drules have intergranular transparent pale brown
glass. In others the glass is turbid and partly
devitrified. Yellowish brown limonitic staining
pervades the section, and patches and veinlets of
reddish brown limonite are common. Microprobe
analyses show olivine ranging in composition
from Fas to Fa38, with a mean of Fais; the pyrox-
ene is relatively uniform in iron content
but shows a considerable range in calcium
(Woo.3-8.5). The low content of nickel-iron and
troilite suggest L group, and the meteorite is
classified L3.
ALHA77140 (78.6 g).?The specimen is
roughly conical. The basal portion is irregular
and appears to be broken surface. The remainder
of the surface is extensively weathered, making it
difficult to tell how much fusion crust remains.
The entire meteorite (4.6 X 3.3 X 3.0 cm) is a
dark reddish brown with considerable iron-oxide
staining. Small (~ 1 mm) metallic and many light
colored inclusions, chondrules and lithic frag-
ments (?) are visible in the gray matrix material
on the sawed surface of the stone. However, some
areas of the stone are iron oxide-stained. A small,
thin, white, presumably evaporite, deposit is pres-
ent on this stone.
The polished thin section (Figure 12a) shows
an elliptical nonchondritic enclave (8X5 mm),
completely enclosed in chondritic material. The
enclave consists of polysynthetically twinned
clinoenstatite (with a range of composition, av-
eraging Woo.2Fs7En93) poikilitically enclosing ir-
regular to globular isotropic or weakly anisotropic
masses. These masses range in composition (SiO2
18 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
59% to 83%, FeO 15% to 31%, MgO 5% to 9%,
K2O 2.7% to 4.3%, Na2O 0.6% to 2.5%, A12O3
-0.3%, CaO, TiO2, <0.1%); they appear to be
devitrified glass, and some analyses are close to
that of merrihueite. The chondritic portion con-
sists of a close-packed mass of chondrules, with a
relatively small amount of fine-grained matrix.
Chondrules range in diameter from 0.2 to 2 mm,
and exhibit a variety of form and structure; the
most common type consists of granular aggregates
of olivine and polysynthetically twinned clino-
pyroxene, commonly with a little interstitial glass.
Both olivine and clinopyroxene have a wide range
of composition. Olivine ranges from Fas to Fa44,
with an average of Fa25; pyroxene ranges from
Fs2 to Fsi7, with an average of Fs7 and a low
calcium content, averaging 0.2% CaO. Troilite
and nickel-iron are interstitial to the chondrules,
and part of the nickel-iron has weathered to
limonitic material. The highly variable composi-
tion of olivine and pyroxene indicates a type 3
chondrite, and the mean composition of the oli-
vine and the amount of nickel-iron suggest L
group, so the meteorite is tentatively classified
L3.
ALHA77160 (70.4 g), 77164 (38.1 g), 77165
(30.5 g).?These three pebble-sized meteorites are
so similar in physical appearance and petrogra-
phy that they are described together; they may
be different pieces of the same meteorite. Al-
though some fusion crust is still present, most of
the surface of these stones is dark brown and has
a patina that probably resulted from chemical
weathering and wind polishing. All three speci-
mens have broken surfaces and are not, therefore,
complete.
Thin sections (Figure 126) show abundant
chondrules, 0.2-2.5 mm diameter, in a minimal
amount of dark fine-grained matrix; some chon-
drules are spherical, but many are elliptical to
irregular in form. The chondrules are composed
mainly of barred or porphyritic olivine, some
with polysynthetically twinned clinopyroxene. In-
terstitial glass in chondrules is pale gray, trans-
parent to turbid. Minor subequal amounts of
troilite and nickel-iron are present, the nickel-iron
is extensively altered to red-brown limonitic ma-
terial, which pervades the section along chondrule
boundaries. Microprobe analyses show a wide
range of olivine composition, Fa3-Fa46, and a
similar range in pyroxene composition. This
range in composition, together with the presence
of glass and twinned clinopyroxene, indicates
type 3, and the small amount of nickel-iron sug-
gests L group; these meteorites, therefore, are
classified L3 chondrites.
ALHA77167 (611 g).?This is an angular spec-
imen (Figure 13), approximately 12.5 X 8.0 X 6.0
cm, and is weathered very dark reddish brown.
The S surface has small remnants of fusion crust,
but the other surfaces are broken. Fractures are
present on the N, S, and B surfaces. Some light-
colored angular clasts and chondrules, as much
as 0.5 cm in diameter, are apparent through the
weathering rind. Many small holes are distrib-
uted randomly over the exterior of the stone,
presumably due to the weathering out of lithic
clasts and chondrules. When the sample was
cleaved it broke into many pieces, none of which
exposed fresh unweathered material.
The polished thin section shows a closely
packed aggregate of chondrules and chondrule
fragments, with a minimal amount of dark fine-
grained matrix. The chondrules range from 0.2
FIGURE 13.?ALHA77167, L3 chondrite; a deeply fractured
stone with a pitted surface, probably produced by the weath-
ering out of lithic clasts and chondrules.
NUMBER 23 19
FIGURE 14.?ALHA77214, L3 chondrite: a, Note well-developed fissuring and remnants of
original surface on lower part, b, Photomicrograph of thin section (width of field is 2.0 mm),
showing part of elliptical granular inclusion (p. 20).
mm to 1.5 mm in diameter, and show a variety
of types, the most common being granular olivine,
olivine-pyroxene, and fine-grained pyroxene
(commonly radiating). The pyroxene is polysyn-
thetically twinned clinopyroxene. The granular
chondrules contain intergranular glass, mostly
turbid and partly devitrified, but rarely transpar-
ent and pale violet in color. Minor amounts of
nickel-iron and troilite are present, commonly
concentrated on the surface of chondrules. The
meteorite is weathered extensively, with brown
limonitic staining pervading the section and nu-
merous veins and small patches of limonite
throughout. Microprobe analyses show a wide
range in the composition of olivine (Fa2-Fa4i)
and pyroxene (FS3-FS17); the pyroxene is low-cal-
cium (CaO = 0.2% to 0.5%). This range of com-
position, together with the presence of glass and
twinned clinopyroxene, indicates type 3, and the
small amount of nickel-iron suggests L group; the
meteorite is therefore tentatively classed as an L3
chondrite.
ALHA77214 (2097 g).?The specimen (Figure
14a) is angular (approximately 16 X 7 X 14 cm),
with remnants of fusion crust on 30% of the
surface. Another 30% of the surface may have
been covered with fusion crust that has been
abraded away. The remaining surface is a frac-
ture plane. The stone contains many fissures. The
material near these is severely weathered and
friable. Snow was observed in several of the fis-
sures when the meteorite was removed from cold
storage. A weathering patina, ranging from
brown through brownish black, covers the total
specimen with the exception of the fracture sur-
face. Some oxidized-iron staining is apparent on
the exterior surface; however, the most severe
staining occurs on the material adjacent to the
fissures and on the fracture surface. A number of
chondrules are visible in the hand specimen.
The polished thin section shows considerable
weathering, with much of the metal oxidized to
limonite. However, the narrow end of the section
shows much more weathering than the wider end,
giving some hope that the deep interior of the
stone may be much fresher. Troilite is abundant
and outlines the margins of many chondrules.
Chondrule margins are sharply distinguishable
from the fine-grained matrix. At least two chon-
drules contain fresh pinkish brown glass that
shows strain isogyres in crossed polarizers. Most
chondrules appear to be fluid-drop chondrules,
and some are broken or are only small portions of
their original volumes, as judged from their radii
20 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
of curvature. Some chondrules, ranging in size to
more than 4 mm in maximum diameter, contain
large euhedral olivine crystals, and some large
euhedral olivine and pyroxene grains occur as
individual crystals. A number of the fluid-drop
and lithic chondrules appear to be surrounded by
fine-grained troilite-rich dark rims or rinds, but
the exact nature of the rims is difficult to distin-
guish because of the weathering. Microprobe
analyses show a wide range in olivine composi-
tion, Fai-Fa49. The section contains an elliptical
body 3 mm across (a chondrule or a lithic frag-
ment) with a poikilitic texture of orthopyroxene
(\V01Fs13En86) enclosing smaller round grains of
olivine Fai7-2o, averaging Fai8 and another pyrox-
ene (?) (Figure 14b). Other lithic fragments are
present. A chemical analysis of this meteorite is
given in Appendix 2.
ALHA77249 (504 g).?The sample has broken
surfaces and is only partially covered with fusion
crust (Figure 15a). The S and T surfaces have
very thin, dull black patches of fusion crust. The
B surface has thin, shiny black fusion crust, por-
tions of which have weathered to reddish brown.
There are numerous inclusions, both lithic clasts
and chondrules, visible through the reddish
brown oxidation rind. The largest chondrule is
approximately 0.5 cm in diameter and is lighter
colored than the surrounding matrix. A few in-
clusions that are darker than the matrix also are
observed; however, they are not as numerous or
as large. The sample is angular, 11.0 X 6.5 X 5.0
cm, and has many obvious fractures on the exte-
rior surface.
The thin section shows an aggregate of well-
defined chondrules, 0.3-2.1 mm in diameter, set
in a relatively small amount of fine-grained
groundmass. A wide variety of chondrule types is
present, the most common being barred olivine,
porphyritic olivine, granular olivine-pyroxene,
and fine-grained pyroxene. The olivine chon-
drules commonly have interstitial glass, mostly
turbid and partly devitrified, but rarely transpar-
ent and pale brown. Pyroxene grains show poly-
synthetic twinning. Sparse nickel-iron and troilite
are concentrated on the surfaces of chondrules.
Limonitic staining pervades the section, and scat-
tered grains of reddish brown limonite are pres-
ent. Microprobe analyses show a wide range in
the composition of olivine (Fa7-Fa35, average
Fan) and pyroxene (FS2-FS25, average Fsn). This
range of composition, together with the presence
of glass and twinned clinopyroxene, indicates
type 3, and the small amount of nickel-iron sug-
gests L group; the meteorite, therefore, is tenta-
tively classified as an L3 chondrite.
FIGURE 15.?L3 chondrites: a, ALHA77249, deeply fractured stone with remnants of fusion
crust (lower right), b, ALHA7726O, a fractured stone with fusion crust on the lower part.
NUMBER 23 21
ALHA7726O (744 g).?The specimen is oblong
(Figure 156), 14.0 X 5.5 X 6.5 cm. A thin fusion
crust, approximately 0.5 mm, covers 50% of the
specimen. There are several fractures that pene-
trate the stone, and snow was preserved in these
when it was removed from cold-storage. Light
colored, lithic clasts and chondrules, as much as
0.5 cm in maximum length, were observed on the
fractured surfaces. Apparently, the reddish brown
color of the weathering rind masks out the darker
inclusions on the exterior surface. The meteorite
appears to be weathered throughout.
The polished thin section shows well-developed
chondritic structure. The chondrules range from
0.2-1.5 mm in diameter, and some of the chon-
drules are irregular or broken. A variety of chon-
drule types is present, the most common being
barred olivine, granular olivine-pyroxene, and
fine-grained radiating pyroxene. The barred and
granular chondrules have interstitial glass, mostly
turbid and partly devitrified, but occasionally
transparent and pale brown. Much of the pyrox-
ene is polysynthetically twinned clinopyroxene.
The groundmass is fine-grained olivine and py-
roxene, with minor subequal amounts of nickel-
iron and troilite. Limonitic staining and rare
patches of limonite are present throughout the
section. Microprobe analyses show a wide range
of composition for both olivine (Fa7_23, average
Fai6) and pyroxene (Fsi_28, average Fsn). The
wide range of composition of olivine and pyrox-
ene indicates a type 3 chondrite, and the small
amount of nickel-iron suggests L group, thus the
meteorite tentatively is classified L3.
CLASS LL3
FIGURES 16, 17
ALHA76004 (305 g).?This meteorite was col-
lected by the 1976-77 party. Olsen, et al. (1978:
214-216) described it (as Allan Hills #4) as fol-
lows:
[It] is a very heterogeneous breccia consisting of chondrules
and chondrule fragments, clasts of several different crystal-
line rocks, clasts of glass, and quenched glasses that are
interstitial to the clasts .... Thin-section examination shows
a low metal/sulfide ratio, which is appropriate for an LL-
group chondrite. Four thin sections showed metal present
between 1 and 4% .... A random survey of olivine and
pyroxene compositions in a thin section yield ranges from
Fao to Fa34, and Fso to FS53. When plotted on a histogram
there are no peak compositions evident for either mineral.
Minor phases include plagioclase, nepheline, fassaite, chrom-
ite, and other spinel-group phases.
ALHA77278 (313 g).?This is a moderately
rounded conical specimen (Figure 16), approxi-
mately 8.0 X 5.5 X 4.5 cm, and appears to be a
FIGURE 16.?ALHA77278, LL3 chondrite: a, Note conical form, b, Posterior surface showing
radial flow lines in fusion crust.
22 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
complete stone (except the B surface). Approxi-
mately 95% of the surface area is covered by dull
black fusion crust that is ?1-2 mm thick. The
fusion crust on the B (posterior) surface is reddish,
shows well-developed radial flow lines, and is
more oxidized than the other surfaces. Several
spots (~1 cm diameter), where the fusion crust
has been plucked, reveal interior material that is
dark gray and moderately stained by oxidized
iron. No weathering rind is present; however,
some of the near-surface clasts are highly weath-
ered, but the matrix is not.
The polished thin section (Figure 1 la) shows a
FIGURE 17.?LL3 chondrites: a, ALHA77278, photomicro-
graph of thin section (width of field is 2.0 mm); the center
of the photograph is occupied by the carbonaceous (?) en-
clave described on p. 22, and also shows part of the granular
olivine-orthopyroxene enclave, b, ALHA77304, fusion crust
covers most of the surface, but has spalled off in small areas,
revealing matrix material with numerous chondrules and
lithic clasts.
closely-packed aggregate of spherical to ellipso-
idal chondrules (0.3-1.8 mm diameter) with in-
terstitial nickel-iron and troilite (concentrated as
rims to chondrules) and relatively little matrix.
Most chondrules consist of granular or porphyri-
tic olivine, commonly accompanied by polysyn-
thetically twinned clinopyroxene, and with par-
tially devitrified glass between the mineral grains.
Microprobe analyses show that both olivine and
pyroxene have a range of composition; olivine
ranges from Fan to Fa29, with a mean of Fa24,
and pyroxene is low-calcium (Ca = 0.1% to 0.4%)
ranging from Fsg to FS21, with a mean of Fsi2.
Some unusual enclaves were noted in the section.
One, 1.5 mm across, consists of numerous small
(maximum 0.2 mm) grains of olivine and pyrox-
ene in a brown-black semitranslucent, possibly
carbonaceous matrix. Another, 3 mm long, con-
sists of an aggregate of olivine (composition Fai3-
Fa26) and orthopyroxene (FS16-17) grains with a
little interstitial turbid glass. The section shows a
slight amount of yellow-brown limonitic staining,
concentrated near the fusion crust. A chemical
analysis of this meteorite is given in Appendix 2.
ALHA77304 (650 g).?Dull, brownish black,
fusion crust, approximately 0.5 to 1 mm thick,
covers all but the W surface of this angular, 9.5
X 8.0 X 6.5 cm, sample (Figure \lb). On the W
surface and small areas where the fusion crust has
been plucked away, greenish matrix material
with numerous chondrules and irregular lithic
clasts, ranging from light to dark gray, and as
much as 1 cm in diameter are exposed. A fracture
on the B surface appears to penetrate the entire
stone. When the meteorite was cleaved in half,
haloing effects were observed around some inclu-
sions in the interior of the stone. There is no
obvious weathering rind.
The section shows a closely packed aggregate
of chondrules with a minimum amount of fine-
grained matrix; a small amount of troilite and
nickel-iron is present in the matrix. Some of the
chondrules are unusually large, ranging up to as
much as 3 mm in diameter. The most common
types are barred and porphyritic olivine chon-
drules with interstitial glass; some of the glass is
isotropic and transparent, but most is turbid and
NUMBER 23 23
partially devitrified. Polysynthetically twinned
clinopyroxene occurs with the olivine in some
chondrules. A 6 X 3 mm enclave, consisting of
closely packed idiomorphic olivine crystals with
interstitial turbid brown glass, is present at one
edge of the section. Brown limonitic staining
pervades the section. Microprobe analyses show
olivine (Faig-27, average Fa24) and pyroxene
(FS13-19, average Fsis) have a wide range of com-
position; the olivine in the enclave has uniform
composition, Fa25. A few grains of calcic plagio-
clase, averaging An77, were noted. The low con-
tent of nickel-iron and troilite suggest LL group,
and the wide range of olivine and pyroxene com-
positions type 3; thus the meteorite tentatively is
classified LL3.
CLASS H4
FIGURES 18, 19
ALHA77004 (2230 g).?The angular specimen,
7.0 X 5.5 X 2.0 cm (Figure 18a), has many parallel
fractures. Only the B surface has dull brownish
black fusion crust. The other surfaces are weath-
FIGURE 18.?H4 chondrites: a, ALHA77OO4, severely weathered stone with deep parallel
fractures, b, ALHA7719O, a tabular specimen with patchy remnants of dull black fusion crust.
c, ALHA77191, the area photographed is a concave fracture surface, stained red-brown with
iron oxides produced by weathering, d, ALHA772O8, a severely weathered and deeply fractured
stone, without fusion crust.
24 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
ered orangish brown. Because of the severity of
the weathering, it is impossible to define the
shape, size, and color of the inclusions, which are
distinguished by textural changes on the exterior
of the stone. When attempting to obtain a thin
section sample, the stone broke into six pieces,
none of which exposed unweathered material.
ALHA7719O (387 g).?The specimen is ap-
proximately 11.0 X 6.0 X 3.4 cm and is tabular
(Figure 18b). The N, T, and S surfaces have
remnants of a thin, dull black fusion crust. The
E surface is highly oxidized, reddish brown and
a fracture surface. No unweathered material was
exposed in the meteorite when it was cleaved in
half. The sample is a uniform reddish brown
throughout. After drying in the nitrogen cabinet
for 48 hours (after cleaving), a small spot area of
white material, presumably evaporites, developed
on the freshly exposed interior surface.
ALHA77191 (642 g).?This 11.0 X 7.0 X 5.0
cm specimen is semi-rounded (Figure 18<:); how-
ever, the B surface is concave. This stone is ex-
tremely weathered, making it difficult to deter-
mine the amount of fusion crust present. The
oxidation staining is semiglossy and reddish
brown. Parallel fractures, in the north-south di-
rection, penetrate the stone. No unweathered ma-
terial was exposed by cleaving the stone in half;
the same reddish brown oxidation staining that
is present on the exterior of the stone penetrates
throughout the specimen with the exception of a
few areas, approximately 0.5 cm in diameter,
which are slightly lighter. According to field
notes, this is believed to be one of a group of 19
samples that are likely to be a single fall.
ALHA77192 (845 g).?The angular specimen
(~9.0 X 8.0 X 15.0 cm) is void of fusion crust.
The entire stone is weathered reddish brown, with
the exception of a few small areas of gray matrix
material that was exposed when the stone was
cleaved in half. The severity of the weathering
masks any textural characteristics. This is one of
the 19 specimens that W.A. Cassidy believes to
be related. The meteorites that have been initially
processed and comprise this group are:
ALHA77004, 77190, 77191, 77192, and 77233.
ALHA772O8 (1733 g).?The specimen is an-
gular, highly fractured, and severely weathered
(Figure I8d). No fusion crust remains on the
specimen. The fractures appear to penetrate
throughout the 13.75 X 10.0 X 9.0 cm stone.
Numerous chondrules and irregularly shaped
fragments, as much as 1.0 cm in diameter, are
apparent. When the stone was cleaved, only a
few areas, ~2 mm in diameter, appeared un-
weathered and grayish. Approximately 95% to
97% of the interior surface was the same reddish
brown color as the exterior of the stone.
ALHA77224 (787 g).?This is an angular spec-
imen, approximately 13 X 14 cm, extremely
weathered and friable, with many fissures that
appear to penetrate throughout the meteorite.
One surface shows patches of fusion crust (very
thin) and remnants of regmaglypts. Small inclu-
sions were observed on the weathered surfaces.
ALHA77233 (4087 g).?This stone is 15.0 X
14.0 X 10.5 cm (Figure 19a). Thin (<1 mm), dull
black, patchy fusion crust is present on the S and
E surfaces. The remainder of the stone is shiny
reddish brown. White deposits, presumably eva-
porites, are present in minor cracks on all exterior
surfaces. Chipping and cleaving of the specimen
did not expose any unweathered material.
ALHA77262 (862 g).?The specimen is covered
by dull, brownish black, polygonally fractured,
fusion crust on all surfaces with the exception of
the B surface, which is only partially covered.
The angular stone (Figure 19c) is approximately
9.5 X 7.5 X 6.5 cm. Snow/ice was present on the
sample when it was removed from cold storage.
Areas of the sample are covered with a thin white
coating, presumably evaporites. After drying the
sample in the nitrogen cabinet, additional white
material, which was not present during initial
processing, was noted around many of the surface
cracks. Small, irregular, and round inclusions are
apparent on the sawed surface. Metallic particles
present in the light gray matrix material of the
sawed surface have oxidation halos. A weathering
rind, as much as 0.8 cm thick, is present on the
stone.
The thin sections (Figure 19^ d) of the H4
25
FIGURE 19.?H4 chondrites: a, ALHA77233, severely weathered and moderately fractured
stone; b, photomicrograph of thin section (width of field is 2.0 mm), showing well-developed
chondrules in a granular matrix, c, ALHA77262, angular, roughly conical stone covered with
fusion crust except on the base; d, photomicrograph of thin section (width of field is 2.0 mm),
showing large porphyritic and granular olivine chondrules.
chondrites resemble each other closely. They all
show well-developed chondritic structure, chon-
drules averaging 0.5-1.0 mm in diameter.
(ALHA77233 has some unusually large chon-
drules, ranging up to 2.8 mm in diameter.) A
variety of chondrule types is present, the com-
monest being porphyritic to granular olivine,
barred olivine, fine-grained pyroxene, and gran-
ular olivine-pyroxene. The chondrules are set in
a fine-grained granular matrix consisting largely
of olivine and pyroxene, with minor amounts of
nickel-iron and troilite (nickel-iron in greater
amount than troilite). Some of the pyroxene in
the chondrules and in the matrix is polysynthe-
tically twinned clinobronzite. All these meteorites
are extensively weathered with brown limonitic
staining throughout the sections, and veins and
patches of limonite often associated with the
nickel-iron grains. The section of 77190 is distin-
guished from the other H4 chondrites by the
partial fragmentation of many of the chondrules,
possibly shocked-induced. Microprobe analyses
(Appendix 1) show variable olivine and pyroxene
compositions (except in 77208 and 77224). Aver-
26
age composition of olivine ranges from Fai6 to
Fai9, of pyroxene from Fsi4 to FS17.
CLASS L4
FIGURES 20-22
ALHA77215 (820 g).?The S surface of this
specimen mostly is weathered reddish brown;
however, a small remnant of fusion crust remains
(Figure 20a). The E, W, and N surfaces are
fractures that show numerous chondrules and
lithic clasts. The largest chondrule is approxi-
mately 0.5 cm in diameter. Both the chondrules
and lithic clasts commonly are lighter in color
than the surrounding gray matrix. The surfaces
not covered with weathering rind range from
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
greenish brown to reddish brown. There are nu-
merous fractures over the surface. The meteorite
is approximately 13.0 X 7.0 X 7.0 cm.
ALHA77216 (1470 g).?Ice was present on the
sample when it was removed from cold storage.
Dull black fusion crust (as much 0.5 mm thick)
covers half of the surface (Figure 20b). The sample
is approximately 15.0 X 9.0 X 8.0 cm. Field
photographs show that the T and N surfaces were
in contact with the ice at time of recovery. The
overall color is greenish gray. Numerous inclu-
sions (rounded and irregular), ranging to more
than 2.0 cm in diameter, are apparent on the
fracture surfaces; these range from white to whit-
ish gray to dark gray. The fracture surfaces show
different degrees of weathering, presumably due
FIGURE 20.?L4 chondrites: a, ALHA77215, fractured stone
with chondrules and lithic clasts visible on the surface, b,
ALHA77216, with numerous rounded and irregular inclu-
sions, up to 2 cm across, visible on the surface, c,
ALHA77217, white to gray clasts, up to 1.5 cm across, are
visible in the dark matrix.
NUMBER 23 27
to different lengths of surface exposure time. This
meteorite is very heterogeneous on a centimeter
scale. Many fractures penetrate the meteorite.
ALHA77217 (413 g).?This stone is approxi-
mately 9.5 X 7.0 X 4.5 cm (Figure 20c). Fusion
crust (~1 mm thick) covers approximately 20%
of the surface. The remaining surfaces are stained
with hydrous iron oxides. The S surface is only
lightly stained; presumably this is the most re-
cently exposed surface. The broken surface show
distinct clasts ranging from white to dark gray, as
much as 1.5 cm in length. The stone is extremely
heterogeneous on a centimeter scale.
The thin sections of 77215, 77216, and 77217
resemble each other closely. They show well-de-
veloped chondritic structure, with a variety of
chondrule types; chondrules range from 0.3-1.8
mm in diameter. The chondrules are set in a
granular groundmass consisting largely of olivine
and pyroxene, with minor nickel-iron and troilite
in approximately equal amounts. Much of the
pyroxene, especially in the chondrules, is polysyn-
thetically twinned clinopyroxene. Weathering is
slight, being confined to a small amount of li-
monitic staining around the nickel-iron grains.
Microprobe analyses show variability in olivine
and pyroxene compositions; olivine; Fai7-26, av-
erage Fa23j pyroxene, FS9-26, average FS17. The
thin section of 77216 contains three enclaves; two
consist of granular olivine and pyroxene, and
measure at least 3 mm across; the third is an
irregular object 2 mm in maximum dimension,
and consists of small grains of olivine and pyrox-
ene in a translucent brown groundmass. Olivine
and pyroxene in the two granular enclaves have
essentially identical and uniform composition,
Fa24 and Fsig. Olivine in the brown enclave has
uniform composition, Fa24, but the pyroxene is
somewhat variable, FS13-21, average Fsn.
ALHA77215, 77216, and 77217 were collected
in the same restricted area and are very similar in
macroscopic and microscopic appearance. It is
therefore possible that these pieces are related,
probably pieces of the same fall.
ALHA77230 (2473 g).?This is a subrounded
to angular specimen that is a nearly complete
stone (Figure 21a). It is covered with a brownish
black fusion crust, approximately 0.5-1.0 mm
thick, except for some small broken surfaces. The
portion of the fusion crust that was in contact
with the ice at time of recovery has an iridescent
sheen and is more severely weathered than the
upper portion. The specimen has several surface
fissures, along which weathering has penetrated
to a depth of nearly 0.5 mm.
A polished thin section (Figure 2lb) shows a
FIGURE 21.?ALHA77230, L4 chondrite: a, Stone with well-preserved fusion crust, b, Photo-
micrograph of thin section (width of field is 2.0 mm), showing large barred olivine chondrule
and dark gray angular grain, possibly devitrified glass.
28 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
closely packed aggregate of chondrules (0.3-1.0
mm diameter): Some are spherical, but many
appear fragmented and broken. A variety of
chondrule types is present: barred olivine, por-
phyritic olivine, and pyroxene that is either fine-
grained or polysynthetically twinned. Some chon-
drules have interstitial turbid devitrified glass.
Minor subequal amounts of troilite and nickel-
iron are present. A moderate amount of limonitic
staining pervades the section. Fusion crust is pres-
ent on one edge of the section. Microprobe anal-
yses show olivine (Fa22-25, average Fa23) and py-
roxene (Fsi8-29, averaging FS21) of fairly uniform
composition.
ALHA77252 (343 g).?This specimen suffered
considerable damage during transport from the
Antarctic and was noted as consisting of chips
and fines on its arrival in California (Figure 22).
One piece has dull black fusion crust. The matrix
of all pieces is greenish gray and contains many
inclusions ranging to more than 1 cm across.
Many surfaces have an orangish brown weather-
ing rind. This specimen looks very similar in
macroscopic appearance to ALHA77215, 77216,
and 77217.
FIGURE 22.?ALHA77252, L4 chondrite; the stone broke
into numerous fragments during transport from Antarctica,
and light gray chondrules and lithic clasts are visible in the
darker gray matrix; the largest fragment is partly covered
with fusion crust.
The chip from which the thin section was made
showed a marked division into two parts, the
larger dark gray and chondritic, the smaller
(probably a lithic clast) pale gray and granular.
This division is also prominent in the thin section.
The granular part appears to contain some poorly
defined chondrules; in the chondritic part chon-
drules are numerous and well defined, sometimes
broken and fragmentary. Minor subequal
amounts of nickel-iron and troilite are present in
both parts. A small amount of limonitic staining
is present, concentrated around the metal grains.
Microprobe analyses show olivine and pyroxene
in the granular part to have uniform composi-
tions: olivine, Fa25; pyroxene, FS20. Minor plagio-
clase (Ani2) was detected in the granular part.
The chondritic part has variable composition in
the olivine (Fa22-28, average Fa24) and pyroxene
(FS2-22, average Fsis). The meteorite is classified
as an L4 chondrite with lithic clasts.
CLASS H5
FIGURES 23-25
The following chondrites are pebble-sized spec-
imens (Figure 23a) and are very similar in mac-
roscopic and microscopic appearances and in de-
grees of weathering: ALHA77014 (309 g), 77021
(16.7 g), 77025 (19.4 g), 77061 (12.6 g), 77062
(16.7 g), 77064 (6.5 g), 77071 (10.9 g), 77074 (12.1
g), 77086 (19.4 g), 77088 (51.2 g), 77102 (12.3 g),
77118 (7.8 g), 77119 (6.4 g), 77124 (4.4 g), and
77264 (11.0 g). Of these samples only
ALHA77O25, 77119, and 77264 are complete
specimens covered with fusion crust; the others
have suffered various degrees of fracturing.
ALHA77177 (368 g).?The sample is angular
and is approximately 7.0 X 6.5 X 5.5 cm (Figure
23b). This appears to be a complete specimen,
with the exception of a 3.0 X 4.0 cm area, which
has been chipped away. Dull black fusion crust
covers approximately 30 to 40 percent of the
sample. The portion of the sample not covered
with fusion crust is weathered reddish brown. A
yellow-brown clast, ~0.5 cm in diameter, was
observed on the W surface.
NUMBER 23
a
29
ALHA ALHA ALHA
77061 77062 77064 cm cube
ALHA77177
FIGURE 23.?H5 chondrites: a, ALHA77O61, 77062, 77064; pebble-sized chondrites. b,
ALHA77177, an angular stone with a pitted surface, probably produced by the weathering out
of chondrules and lithic clasts.
FIGURE 24.?H5 chondrites: a, ALHA77182, fractured and
weathered stone without fusion crust, b, ALHA77294, a
fractured stone partly coated with fusion crust, c,
ALHA7 7300, note remnants of fusion crust (upper right)
and rough globular-like fracture surface.
30
ALHA77182 (1109 g).?No fusion crust is ap-
parent on this angular specimen, 12.5 X 8.0 X 7.0
cm (Figure 24a). The overall color of the sample
is orangish brown. A band, approximately 1-5
cm wide, of yellowish green material crosses the
meteorite on the E-W axis. It is apparent by
looking at the T surface that this is not just a
surface feature. Many random fractures cover the
surface of the meteorite. Numerous irregular
lithic fragments and chondrules, up to as much
as 0.5 cm in diameter, are apparent. This sample
appears to be exfoliated.
Surfaces revealed by sawing the meteorite in
half exhibit metallic particles, approximately 1-
2 mm in diameter. Three fractures, ~3 cm in
length, are apparent on the cut face. The mete-
orite has no weathering rind and no weathering
is apparent along fractures.
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
ALHA77294 (1351 g).?Polygonally fractured,
dull, brownish black fusion crust, approximately
1 mm thick, covers all surfaces of this meteorite
(?13.5 X 9.0 X 6.0 cm), with the exception of the
edges, which appear to have been spalled (Figure
24b). White material, presumably evaporite de-
posits, fills the grooves in the polygonal fractures
on the B surface. This surface appears more se-
verely weathered than the other surfaces, owing
to the presence of rounded areas of oxidation
staining. The matrix of the stone is whitish gray
with areas of orangish brown oxidation stain.
Chondrules and irregular inclusions (lithic frag-
ments?), as much as ~2 mm in diameter and both
lighter and darker than the matrix, are apparent
throughout the sample. After 60 hours of drying
in the nitrogen cabinet, a heavy crystalline de-
posit was noted on the corner of the W, B, and S
FIGURE 25.?H5 chondrites: a, ALHA771O2, photomicrograph of thin section (width of field is
2.0 mm); note two juxtaposed barred olivine chondrules apparently fused together, b,
ALHA77264, photomicrograph of thin section (width of field is 2.0 mm).
NUMBER 23 31
surfaces. When the stone was cut in half, no
weathering rind was visible. Approximately 15%
to 20% of the sawed surface appears to be metallic
particles.
ALHA773OO (235 g).?This stone is 9.0 X 5.0
X 4.5 cm and oblong (Figure 24c). Half the
surface appears to have had fusion crust that has
been almost completely abraded, leaving only
small particles of dull, brown fusion crust. Half
the specimen has a rough, globular-like fracture
surface. The exterior is weathered uniformly to
dark orangish brown.
When the sample was cleaved in half, no un-
weathered material was exposed. The severity of
the weathering caused the sample to crumble into
many pieces during handling for photography.
In thin sections (Figure 25) all the H5 chon-
drites show a well-developed chondritic structure,
with a variety of chondrule types, the commonest
being barred olivine, granular and porphyritic
olivine, and fine-grained pyroxene. The matrix is
fine- to medium-grained, and consists largely of
olivine and pyroxene, with minor amounts of
nickel-iron, troilite, and small grains of sodic
plagioclase. The compositions of the olivine (Fais-
19) and orthopyroxene (Fsi5_i7) are essentially uni-
form within the individual specimens.
The following specimens are possible pieces of
a single meteorite: ALHA77O21, 77025, 77061,
77062, 77064, 77071, 77074, 77086, 77088. Con-
firmation of these and possible additional group-
ings requires additional research.
CLASS L5
FIGURES 26, 27
ALHA 77002 (235 g).?The meteorite, approx-
imately 6.5 X 4.5 X 5.0 cm (Figure 26a), is covered
completely with brownish black thin fusion crust
that shows appreciable weathering. One large
fracture is present. When this stone was cut, fresh
metal and rounded inclusions were apparent in
the medium gray matrix. Some of the clasts are
severely weathered, making the sawed surface
appear orangish brown.
In thin section (Figure 266) chondrules are
prominent and well-defined. The matrix is dom-
inantly olivine, in angular grains as much as 1.0
mm in maximum dimensions, with lesser
amounts of orthopyroxene. Minor minerals in the
matrix are nickel-iron, troilite, and chromite; pla-
gioclase is present as very small grains that are
difficult to recognize. The section is stained brown
with limonitic materials, and the metal grains are
corroded, evidently by terrestrial weathering;
troilite is unaffected. Microprobe analyses show
FIGURE 26.?L5 chondrites: a, ALHA77OO2, angular stone completely covered with fusion crust.
b, ALHA77OO2, photomicrograph of thin section (width of field is 2.0 mm); prominent
chondrules in a granular matrix.
32 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
uniform composition of the olivine (Fa25) and
orthopyroxene (W01.2 En77 FS22); plagioclase av-
erages Abg4 Anio Or6, but has a slightly wider
range of composition.
ALHA77254 (246 g).?Very thin dull black
fusion crust is present on two surfaces (T and N)
of the meteorite (Figure 27). The surfaces free of
fusion crust have a dull orangish brown weath-
ering patina, with the exception of the B surface,
which is shiny or orangish brown. From field
photographs it was determined that this angular
specimen had its B surface in contact with the ice
at the time of recovery. The B surface has slick-
ensides. The specimen is 10.5 X 5.0 X 4.0 cm.
Many inclusions ranging to as much as 1 cm in
maximum length are visible on the sawed surface
of the meteorite. Discoloration due to weathering
of the outermost material was observed to a depth
of approximately 1.5 cm along the surface.
The section shows well-developed chondritic
structure, the chondrules ranging from 0.3 to 2.1
mm in diameter; a variety of types is present, the
most common being barred olivine, granular oli-
vine and olivine-pyroxene, and radiating pyrox-
ene. The chondrules are set in a granular matrix
of olivine and orthopyroxene, with minor sub-
equal amounts of nickel-iron and troilite. Limon-
itic staining and a few patches of reddish brown
limonite are associated with the metal grains.
Fusion crust is present along one edge of the
section. Microprobe analyses show olivine (Fa23)
and orthopyroxene (FS20) of essentially uniform
composition.
f cm cube
FIGURE 27.-
ALHA77254
-ALHA77254, L5 chondrite; the B surface is a
slickensided fracture surface.
CLASS H6
FIGURE 28
ALHA76006 (1137 g) and 76008 (1150 g).?
These specimens were collected by the 1976-77
party and have been described by Olsen, et al.
(1978). They report very similar compositions for
the principal minerals: olivine, Fais.3 (76006),
Faig.2 (76008); pyroxene, Fsi6.i (76006), Fsi&s
(76008); plagioclase, Am3.6 (76006), Am3.6
(76008). However, 76006 and 76008 appear to be
different meteorites. Olsen, et al. (1978: 211-212)
state:
L. Rancitelli (personal communication) has measured
terrestrial ages on several of these Antarctic chondrites. All
the ages are on the order of 105 years, however, Allan Hills
#8 [i.e., 76008] has a terrestrial age of 1.7 X 106 years,
making it one of the oldest falls known. Because of this
venerable terrestrial age it was thought worthwhile to per-
form a bulk analysis The analysis is that of a normal H-
group chondrite that has been very weathered. The H2O+
value, 2.20%, is far above the average for this group, and the
carbon content, 0.20%, is twice the average for the group.
The bound water content suggests the presence of relatively
stable secondary hydrated minerals that were formed during
the almost two million year long weathering period... .The
higher than normal carbon content suggests carbonate con-
tamination during the long weathering history.
Examination of a specimen and thin section of
ALHA76008 in the Smithsonian Institution (Ma-
son, pers. comm.) shows that this meteorite is
heavily veined with limonite near the surface, but
the interior is relatively unweathered; there is less
limonite in association with interior metal grains
in 76008 than in 76006. Planimetric analysis of
the thin section of 76008 gives 17.7 weight percent
of metal; this is not much less than the average
for unweathered H-group chondrites (18.6%) and
is considerably greater than given by the chemical
analysis (8.5%), which suggests that the sample
for chemical analysis was taken from near-surface
weathered material. Many of the chondrites col-
lected by the 1977-78 party are far more weath-
ered than76008, and might therefore be expected
to give very old terrestrial ages. However, weath-
ering is a function not only of time but also of
composition and structure of the meteorite; some
newly fallen chondrites show a rapid develop-
NUMBER 23
ment of rusting, whereas others remain unaf-
fected. Caution should therefore be used in cor-
relating degree of weathering with terrestrial age.
Kirsten, Ries, and Fireman (1978) have calcu-
lated a cosmic-ray exposure age of 20 ? 2 my for
76006 and 1.5 ? 0.2 my for ALHA76008.
ALHA77144 (7.9 g) and 77148 (13.1 g).?Of
the H6 chondrites collected by the 1977-78 party,
77144 and 77148 are small pebbles partially or
wholly coated with fusion crust. Both are consid-
erably weathered; yellow-brown limonitic stain-
ing pervades the thin sections.
ALHA77258 (597 g).?This five-sided speci-
men is completely covered with fusion crust, with
the exception of one small area. The matrix ma-
terial is yellowish brown with small metallic par-
ticles.
ALHA77271 (610 g).?This completely
33
rounded stone, 8.0 X 7.5 X 5.0 cm has about 25%
of the surface covered with small patches of dull
black fusion crust. Where the fusion crust is miss-
ing, the surface is weathered dark brown; small
inclusions are visible on this surface.
ALHA77285 (271 g).?This semi-rounded
specimen, 5.0 X 6.0 X 6.5 cm, is comprised of
three individual pieces that fit together. The me-
teorite has a reddish brown weathering patina.
Only one small patch of weathered fusion crust
is present on the ? B surface. No unweathered
material was exposed during attempts to obtain
material suitable for thin sections.
ALHA77288 (1880 g).?This is an angular
stone, 12 X 10 X 8 cm. Four surfaces are rounded
and smooth with brown weathering rind and
patches of dull black fusion crust ~ 1-2 mm thick.
The other surfaces represent fracture planes and
FIGURE 28.?H6 chondrites: a, ALHA77271, photomicrograph of thin section (width of field is
2.0 mm); chondrules are sparse and tend to merge with the granular matrix, b, ALHA77288,
photomicrograph of thin section (width of field is 2.0 mm); chondrites are scarcely discernible
from the granular matrix.
34
also are covered with brown weathering rind;
inclusions are apparent on the severely weathered
surfaces. Numerous fractures penetrate the stone.
Petrographically, all the H6 chondrites are very
similar (Figure 28). Chondrules are sparse and
poorly defined, tending to merge with the gran-
ular groundmass, which consists mainly of olivine
and pyroxene, with minor amounts of nickel-iron,
sodic plagioclase, and troilite, and accessory
chromite. Microprobe analyses show olivine
(Faig) and orthopyroxene (Fsn) of essentially uni-
form composition.
MBRA76001 (17881 g).?These two stones,
originally called "Mt. Baldr a and b," were col-
lected by the 1976-77 party about 100 kilometers
south of the Allan Hills. Olsen, et al. (1978: 210)
comment:
The close similarity between Mt. Baldr a and Mt. Baldr
b lead us to believe they are paired finds. They were found
less than a kilometer apart, and no other meteorites were
present in the area... .Thus, the two Mt. Baldr specimens
could be simply a single fall in that area, with some subse-
quent movement by the glacial tongue that ultimately ava-
lanches into the upper end of the Wright Valley. Whether
these constitute a single meteorite, or two meteorites cannot
be decided absolutely until rare-gas data are obtained.
Olsen et al., classify these chondrites as H6, but
Yanai, Miyamoto, and Takeda (1978) classify
Mt. Baldr a as H4-5 and Mt. Baldr b as H5-6.
Weber and Schultz (1978) have shown from rare-
gas data that Mt. Baldr a and b belong to the
same fall.
CLASS L6
FIGURES 29, 30
The following chondrites are classified as L6:
ALHA76001 (20151 g), 76003 (10495 g), 76007
(410 g), 76009 (407000 g); ALHA77OO1 (252 g),
77150 (58.3 g), 77155 (305 g), 77231 (9270 g),
77261 (412 g), 77269 (1045 g), 77270 (589 g),
77272 (674 g), 77273 (492 g), 77277 (143 g), 77280
(3226 g), 77281 (1231 g), 77282 (4127 g), 77284
(376 g), 77296 (963 g), 77297 (952 g), 77305
(940 g).
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
TABLE 1.?
ALHA
76001
76003
76007
76009
-Composition of four 1976-77
(after Olsen, et al., 1978)
Olivine
(Fa)
24.5
24.6
24.4
23.1
Pyroxene
(Fs)
20.9
21.0
21.2
20.7
L6 chondrites
Plagioclase
(An)
10.8
10.8
10.8
10.8
Of the four L6 chondrites collected by the
1976-77 party, ALHA76009 was notable as being
the largest meteorite yet discovered in Antarctica;
it was found as a group of 33 fragments, the three
largest weighing respectively 114, 102, and 58 kg.
(In December 1978, a 138 kg iron and several
smaller masses of the same meteorite were found
on the slopes of Derrick Peak, near the Darwin
glacier (80 ?S 158?E).) These four chondrites are
very similar in megascopic appearance, degree of
weathering (minor, confined to limonitic staining
around metal grains), and composition of princi-
pal minerals (Table 1). Weber and Schultz (1978)
have published He, Ne, and Ar data on these
meteorites, and for 76007, Kirsten, Ries, and
Fireman (1978) have calculated an exposure age
of 22 ? 2 my.
The L6 chondrites collected by the 1977-78
party are partially coated with fusion crust (Fig-
ure 29), except for 77305, on which only traces
remain. Weathering is slight to moderate in most
specimens, being confined to limonitic staining
on the surface and around metal grains in the
interior; in 77150, 77269, and 77273 weathering
is more extensive, with limonitic staining
throughout the polished sections.
Polished thin sections show sparse, poorly de-
fined chondrules, which tend to merge with the
granular groundmass (Figure 30). Principal min-
erals are olivine and orthopyroxene in subequal
amounts, together with minor amounts of plagio-
clase, nickel-iron, troilite, diopside, and accessory
chromite and merillite. Microprobe analyses (Ap-
pendix 1) show essentially uniform compositions
for the principal minerals: olivine, Fa24-25; ortho-
pyroxene, FS20-22; plagioclase, Ann.
FIGURE 29.?L6 chondrites: a, ALHA77272, angular stone, partly coated with fusion crust, b,
ALHA7728O, stone with fusion crust partly spalled away, c, ALHA77281, a completely crusted
stone showing some fracturing, d, ALHA77282, an incompletely crusted stone.
CLASS H?
FIGURE 31
ALHA77081 (8.6 g).?The stone (1.5 X 20 X
1.5 cm) is angular to subrounded. Approximately
60% of the surface is covered by a highly weath-
ered, brownish black to reddish brown fusion
crust and remnants of fusion crust. One broken
surface shows a granular texture and iron-oxide
staining. Several rounded and irregular inclusions
and small metallic particles were apparent in the
whitish gray matrix.
A thin section (Figure 31) shows that this me-
teorite is an equigranular (grains 0.1-0.3 cm in
diameter) aggregate of approximately equal
amounts of olivine and orthopyroxene, with mi-
nor amounts of diopside, plagioclase, nickel-iron,
and troilite, and accessory chromite. Fusion crust
is present along one edge of the section. A mod-
erate amount of yellowish brown limonitic stain
is present, concentrated around nickel-iron grains.
Microprobe analyses show the minerals are uni-
form in composition: olivine, Fan; orthopyrox-
ene, W01.7 Fsn En87; diopside, W045 Fss Enso;
plagioclase, Anis Or4.
The classification of this meteorite presents dif-
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 30.?L6 chondrites: a, ALHA77277, photomicrograph of thin section (width of field is
2.0 mm); chondrules are sparse and tend to merge with the granular matrix, b, ALHA77281,
photomicrograph of thin section (width of field is 1.7 mm); note fusion crust on one edge, and
almost total absence of chondritic structure.
ficulties. The texture is achondritic, but the min-
eralogical composition is similar to that of the H-
group chondrites, which suggests that this mete-
orite may be a completely recrystallized chon-
drite. However, the composition of the olivine
and orthopyroxene is more magnesian than for
the H-group chondrites. The meteorite resembles
some silicate inclusions in iron meteorites. This
meteorite is identical in mineral composition and
structure to Acapulco, a recent Mexican fall,
described by Christophe Michel-Levy and Lorin
(1978).
Achondrites
EUCRITE
FIGURE 32
ALHA76005 (1425 g).?This eucrite was col-
lected by the 1976-77 field party and has been
described in detail by Olsen, et al. (1978:217-
223):
It is pale gray in color and consists of finely divided macro-
crystalline pyroxene-rich matrix that contains abundant
clastic fragments: (1) Clasts of white, plagioclase-rich rocks.
(2) Medium-gray, partly devitrified, cryptocrystalline. (3)
Monomineralic fragments and grains of pyroxene, plagio-
clases, oxide minerals, sulfides, and metal. In overall ap-
pearance it is very similar to some lunar breccias.
They also report (1978:220-221) pyroxene com-
positions ranging from pigeonite (W09 FS39 En52)
to ferroaugite (W032 Fs37 En3i); plagioclase ranges
from An83 to An9i. Weber and Schultz (1978)
have reported He, Ne, and Ar contents in this
meteorite.
ALHA773O2 (235 g).?The meteorite is angu-
lar to subrounded with the approximate dimen-
sions 9.25 X 5.5 X 4.0 cm; it appears to be a
complete stone (Figure 32a). A thin, black, glassy
NUMBER 23 37
? -ijgrfs'*
? \ ** ,".' ? I*1 ,i "hf
FIGURE 31.?ALHA77O81, H?, photomicrograph of thin sec-
tion (width of field is 2.0 mm); an equigranular aggregate
consisting mainly of olivine and orthopyroxene (white to
gray) with accessory nickel-iron, troilite, and chromite
(black).
fusion crust covers about 70% of the surface. In
places the fusion crust has been plucked away
leaving large cavities randomly distributed on the
surface of the stone. The material in these cavities
is fresh and unweathered and shows feldspar
cleavages. One surface has a large 2-cm protrud-
ing gabbroic clast, which is obviously coarser
grained and darker in color than the bulk mete-
orite. Plagioclase crystals in this clast are several
millimeters long. Another surface has an irregu-
larly shaped clast that differs in texture and color
from the rest of the stone.
The thin section (Figure 32?) shows that this
meteorite is a brecciated pyroxene-plagioclase
achondrite (eucrite). It consists largely of pigeon-
ite (~60%) as brown grains, up to 2 mm, and
plagioclase (~35%) as colorless grains, up to 4
mm, in a comminuted groundmass of these min-
FIGURE 32.?ALHA773O2, eucrite: a, Most of the surface is
coated with black glassy fusion crust, b, Photomicrograph of
thin section (width of field is 2.0 mm); an aggregate of
plagioclase (white) and pigeonite (light to dark gray) clasts
in a comminuted groundmass largely made up of the same
minerals.
erals. A little troilite (<1%) and rare minute
grains of nickel-iron are present. Fusion crust rims
part of the thin section. No evidence of weather-
ing is visible. Microprobe analyses show a range
of compositions in the pigeonite: W03-14, En32_56,
Fs37_64; a few grains of subcalcic ferroaugite av-
eraging W025 En27 FS48 were also analyzed. Pla-
gioclase ranges in composition from An75 to Ang4.
38 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
The section contains a large (6 mm) fine-grained
enclave of similar composition.
Miyamoto, Takeda, and Yanai (1979) have
investigated both ALHA76005 and 77302 and
comment: "The similarity of textures and pyrox-
ene compositions of ALHA76005 and 77302 sug-
gests that these meteorites are the fragments of
one and the same fall."
DIOGENITE
FIGURE 33
ALHA77256 (676 g).?The meteorite is
rounded, with the approximate dimensions 9.5
X 7.5 X 6.75 cm; it appears to be a complete
stone (Figure 33a). Patches of dull black fusion
crust are randomly distributed over 15% of the
surface. The crust appears to have been abraded
away from the remaining surface. The areas lack-
ing fusion crust are weathered and vary in color
from yellowish brown to grayish green. Several
patches of iron-oxide staining are present.
The thin section (Figure 33b) consists almost
entirely (~97%) of coarse (grains up to 6 mm)
orthopyroxene clasts, with comminuted grain
boundaries; microprobe analyses give the com-
position \V02Fs23En75. Some orthopyroxene grains
contain small blebs of clinopyroxene, with com-
position Wo46Fs8En46. Accessory minerals include
plagioclase (~1%), troilite (<1%), and very rare
minute grains of nickel-iron. A small area of
limonite was noted, and moderate limonitic stain-
ing along grain boundaries. A chemical analysis
of 77256 is given in Appendix 2.
UREILITE
FIGURE 34
ALHA77257 (1996 g).?The approximate
measurements of the meteorite are 16 X 11 X 9.5
cm; it is not a complete stone (Figure 34a). About
one-half of the surface is rounded and mostly
covered with fusion crust 2 mm thick. Three
fracture planes bound the remainder of the stone.
The fusion crust is dark brown with areas of
reddish (iron oxide?) staining. Small areas of the
FIGURE 33.?ALHA77256; diogenite: a, Residual patches of
black fusion crust coat part of the surface, b, Photomicro-
graph of thin section (width of field is 2.0 mm); consists
almost entirely of orthopyroxene clasts with comminuted
grain boundaries; black is limonite and troilite.
FIGURE 34.?ALHA77257, ureilite: a, Part of the surface is
rounded and covered with fusion crust; the other part is an
irregular fracture, b, Photomicrograph of thin section (width
of field is 2.0 mm); large grains of olivine and pyroxene in
black carbonaceous matrix.
fusion crust have been plucked away, revealing
the crystalline fabric beneath. The fracture sur-
faces are rough, on a millimeter scale, dark
brownish black, and moderately weathered with
small patches of iron oxide stain. Small white to
transparent anhedral grains occur on the surface
of the meteorite, where they are visible in the
field photographs. The grains are aligned in a
strip across the broken surface and part of the
fusion crust. An X-ray powder photograph shows
that these grains are hydromagnesite mixed with
other phases (Marvin, pers. comm.) The interior
consists of grains with well-developed crystal faces
set in a black, fine-grained matrix. Some grains
are covered with a dark stain and others are milky
white.
The thin section (Figure 34b) consists almost
entirely of anhedral to subhedral olivine (~80%)
and pyroxene (~15%); the minerals are fairly
coarse-grained, with olivine grains up to 4 mm,
pyroxene to 3 mm. The olivine grains show un-
dulose extinction. The pyroxene shows coarse
polysynthetic twinning. Grain boundaries are
marked by a concentration of carbonaceous ma-
terial; trace amounts of troilite and nickel-iron,
partly altered to limonite, occur along grain
boundaries. Microprobe analyses show olivine of
variable compositions (Fag_23, average Fai3) and
with unusually high Ca (0.2% to 0.3%) and Cr
(0.3% to 0.4%) contents. The pyroxene is a low-
calcium clinopyroxene with composition averag-
ing \V07En8iFs12. The meteorite is extremely re-
sistant to cutting and polishing, which probably
indicates the presence of diamond, as in other
ureilites.
Compositional data on the pyroxene in this
meteorite have been provided by Takeda, et
al. (1978). A chemical analysis is given in Appen-
dix 2.
ACHONDRITE, UNIQUE
FIGURE 35
ALHA77OO5 (483 g).?The meteorite (Figure
35a), approximately 9.5 X 7.5 X 5.25 cm, is well
rounded on all faces except one, which is a par-
tially broken surface. Small thin patches of dark
fusion crust, randomly distributed, cover approx-
40 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
FIGURE 35.?ALHA77OO5, unique achondrite: a, Well-
rounded stone with small areas of fusion crust, b, Sawn
surface, showing areas of impact melting (finer grained).
c, Photomicrograph of thin section (width of field is 2.0
mm); large grains of olivine (medium gray) and ortho-
pyroxene (pale gray); white is maskelynite, black is mostly
chromite.
imately 5% of the surface. Parts of the stone are
covered by lighter colored vitreous rind that ap-
parently is the lower portion of the fusion crust
that has been abraded. Some partially melted
crystals merge with the glassy rind. On the cut
surface this specimen appears to be unweathered
(Figure 35b). The variation in color suggests het-
erogeneity on a centimeter scale. Areas of the cut
surface show voids as much as 2 mm in diameter.
The larger voids have a crystalline structure on
the surface; however, no crystals extend into the
cavity.
The thin section (Figure 35c) shows that this
meteorite is an achondrite with the following
modal composition (volume percent): olivine
~55, pyroxene ~35, maskelynite ~8, opaques
(mostly chromite, a little ilmenite, and trace
amounts of troilite) ~2. Olivine occurs as some-
what rounded anhedral to subhedral grains, as
much as 2 mm long, and has an unusual pale
brown color; microprobe analyses show a mean
composition of Fa28- Pyroxene occurs as colorless
prismatic crystals as much as 6 mm long, com-
monly poikilitically enclosing olivine; some crys-
tals show coarse polysynthetic twinning; the com-
position ranges somewhat, averaging \V05Fs23
En72. Maskelynite is present as laths interstitial to
olivine and pyroxene; it has labradorite compo-
sition (An53) and contains 0.2% to 0.3% K2O. The
meteorite has been shocked severely, as shown by
the presence of maskelynite, undulose extinction
in the pyroxene, and areas of apparent shock
NUMBER 23 41
melting. No signs of weathering were observed.
ALHA 77005 is a unique achondrite. The oli-
vine is comparable in composition to that in
chassignites, the pyroxene to that in diogenites,
and the bulk composition will thus be interme-
diate between these two classes of achondrites.
These classes of meteorite, however, are almost
plagioclase-free. Maskelynite of the composition
of ALHA77OO5 is known only in the Shergotty
and Zagami achondrites, meteorites which differ
markedly from ALHA7 7005 in that they contain
no olivine and consist largely of calcium-rich
clinopyroxene.
A detailed account of the petrography of
ALHA77OO5 has been published by McSween,
Taylor, and Stolper (1979). A chemical analysis
is given in Appendix 2.
Stony-Irons
MESOSIDERITE
FIGURE 36
ALHA77219 (637 g).?The specimen (Figure
36a) is a fragment (12X8X7 cm) from a larger
stone. It is partly rounded, partly subangular,
and covered with a dark brown weathering rind.
Glassy, dark greenish black, angular to suban-
gular inclusions up to 1 cm across are visible on
the weathered surface; these are probably pyrox-
ene clasts.
The thin section (Figure 36b) is dominated by
large orthopyroxene clasts (up to 6 mm across) in
a groundmass consisting largely of crushed and
comminuted orthopyroxene (grains up to 0.6 mm
across). The groundmass also contains about 20%
of nickel-iron (kamacite and taenite) in grains
averaging about 0.3 mm, occasional grains of
plagioclase (Ango), troilite, chromite, merrillite,
and a silica polymorph (probably tridymite). The
groundmass encloses a rounded aggregate (3 mm
across) of fine-grained (up to 0.15 mm) olivine,
composition Fa26- The composition of the ortho-
pyroxene clasts and groundmass is somewhat var-
iable, FS24-28, with CaO ranging from 0.5% to
2.3%; one grain of diopsidic pyroxene was ana-
lyzed, W043 En45 FS12. The major material of this
a
FIGURE 36.?ALHA77219, mesosiderite: a, Subangular py-
roxene clasts up to 1 cm across are visible on the dark brown
weathered surface, b, Photomicrograph of thin section (width
of field is 2.0 mm); clasts of orthopyroxene (white) in com-
minuted groundmass largely made up of the same mineral;
black is nickel-iron metal.
42 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
section is characteristic of a diogenite; however,
the presence of a considerable amount of nickel-
iron and the olivine enclave suggests a possible
affinity to the mesosiderites.
The identification as a mesosiderite has been
confirmed by examination of a cut surface of the
whole specimen. A chemical analysis is given in
Appendix 2.
Irons
FIGURE 37
ALHA76002 (1510 g).?This meteorite, col-
lected by the 1976-77 party, has been described
by Olsen, et al. (1978:213-214) as follows:
The bulk nickel content is 6.36%, essentially that of its
kamacite. The major phase in the meteorite is kamacite with
only a minor amount of taenite that occurs as darkened
plessite areas. The largest plessite area found in a polished
section of 20 X 25 mm is only 160 X 800 jum. Thus, in the
polished section no Widmanstatten pattern was evident, and
no kamacite band width could be measured. ... In terms of
its structure, mineralogy, and major element chemistry Allan
Hills #2 [now 76002] is like group IIB and IIA irons,
however, in terms of its trace elements (Ga and Ir) it is
associated with the coarse and medium octahedrites of group
IA.
The following trace elements were recorded (in
ppm): Ga 93, As 10, W 1.3, Re 0.26, Ir 2.3, Au
1.4, Cu 135. Olsen, et al. (1978:213) note the
presence of schreibersite and the absence of troil-
ite in the material studied. They also comment
on the presence of a 4 mm thick heat-affected
zone on the outer edge of the meteorite, evidence
that very little weathering or oxidation has taken
place since this iron fell.
PGPA77006 (19068 g).?This meteorite was
collected in January 1978 at the foot of Purgatory
Peak in the Victoria Valley, about 100 km south-
east of Allan Hills, by Steven Kite of a University
of Maine party. When found, it was partly buried
in gravel and sand, and part of the exposed
surface had a metallic sheen, produced by the
sand-blasting effect of the winds.
The meteorite is approximately conical in form,
19 cm across the base and 18 cm high (Figure
37a). The surface shows shallow regmaglypts, and
occasional deeper cylindrical pits, which proba-
bly represent burned-out troilite inclusions (resid-
ual troilite is present in the bottom of one of
them). The area that was buried is clearly marked
by a thin adhering crust of iron oxide and ce-
mented sand grains. No trace of fusion crust
remains, which suggests that this meteorite may
be an old fall (but relatively rapid abrasion of the
surface is to be expected under the climatic con-
ditions at the site of the find).
ALHA77255 (765 g).? The sample is shaped
like a boomerang and is approximately 15.5 X
7.0 X 1.5 cm (Figure 37 b). The two flat surfaces,
B and T, have an iridescent goldish red sheen on
the brownish black fusion crust. The B surface is
darker brownish red than the other surfaces and
is concave. Small regmaglypts, ~ 1 mm or less in
depth, are present on the T and N surfaces. All
corners on the specimen are smooth and rounded.
ALHA77263 (1669 g).?This orangish brown,
angular sample is approximately 15.0 X 5.5 X 8.0
cm (Figure 37^:). All surfaces have regmaglypts;
however, the T surface has smaller regmaglypts,
~3 mm in diameter, than other surfaces that have
regmaglypts as much as 1 inch in diameter. From
field photographs it was determined that the T
surface was in contact with the ice at the time of
recovery; this surface has a more metallic luster
than the other surfaces.
ALHA77289 (2186 g).?This sample is angular
and oblong (22 X 10 X 5 cm). It is orangish
brown and has many regmaglypts (Figure 37d).
The B surface has radial and transverse flow lines
resulting from its orientation during atmospheric
entry. The B surface also shows a zone of prefer-
ential melting (?), ~1 cm wide, that penetrates
through the sample to the T surface; however, it
is only ~0.5 cm wide on this surface.
Discussion
W. A. Cassidy has provided the following list
and notes on possible pairings of some of the
ALHA77 meteorites.
H4: 004, 191, 192, 208, 224, 233.
H5: 014, 264; 021, 061, 062, 064, 071, 086, 088, 102; 118,
119, 124.
H6: 144, 148; 271, 288.
43
i
* H
FIGURE 37.?Irons: a, PGPA77OO6, Purgatory Peak (width of specimen is 19 cm); the bright
areas at the upper right are the sand-abraded surfaces; the lighter colored area on the lower left
is the originally buried portion of the meteorite, b, ALHA77255, thin rounded specimen with
small regmaglypts on the surface, c, ALHA77263, an irregular angular meteorite with a pitted
surface (the surface illustrated was in contact with the ice at the time of collection), d,
ALHA77289, an angular elongated meteorite with a deep fissure, probably a zone of preferential
melting and ablation.
L3: 015, 160, 164, 165, 167, 249, 260; 033, 214.
L4: 215,216,217.
L6: 270, 277, 284; 001, 296, 297; 150, 305; 231, 272, 273,
280.
IRONS: 250, 263, 283, 289, 290.
Two meteorites discovered anywhere else on the Earth's
surface but in Antarctica would be suspected of being a pair
if they were picked up as close to each other as any two
meteorites recovered at Allan Hills. Obviously, therefore,
simple proximity cannot be used as the single criterion for
pairing finds in Antarctica. In the above list the specimens
were initially categorized according to their petrographic
class, and pairings were then generally considered only
within classes. There was one group of five specimens, of
which three are found in this list (L6: 001, 296, and 297),
and another group of 25, of which six are found in this list
(H4: 004, 191, 192, 208, 224 and 233), where the field
evidence strongly suggested pairing within each group.
The first group of five consisted of three specimens found
only centimeters apart that appeared to be fragments of a
single mass, and two specimens discovered together only 40
m away that appeared to be fragments of a single mass. All
five were picked up in a part of the Allan Hills ice patch
where much smaller specimens appear to have been blown
across the ice until stopped by a fringing snowfield. This size
discrepancy, combined with the fact that meteorites the size
44 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
of the two original masses of these five specimens apparently
do not blow across the ice, suggest an original pairing.
All members of the second group (25 pieces) were picked
up on a patch of ice physically separated from the main
Allan Hills occurrence by about 5 km of snow-covered ice.
All were obvious fragments of larger masses, and all looked
very similar. No meteorites of other types have yet been
found on this patch of ice.
Among the remaining suggested pairings, general prox-
imity within the Allan Hills site was the principal criterion
relied upon, although this is weak for the reason given
earlier, and it really is uncertain whether any members of
the same petrographic group should be excluded from con-
sideration as pairs, as long as they have been discovered near
Allan Hills. The irons (ALHA76OO2, 77250, 77255, 77263,
77283, 77289, and 77290) provide a simple example of the
problems involved. Specimens 77250 and 77255 were found
within 500 m of each other, yet their shapes and surface
textures suggest great differences, either in Ni/Fe or in entry
velocity, or in both. Because of this I have not paired them.
On the other hand, because of similarities in shape and
texture, I have suggested that 77250 be paired with four
other irons, two of which were found about 3 km from 77250.
For the 95 classified specimens from the 1976-
77 and 1977-78 Allan Hills collection, the follow-
ing percentages are obtained: chondrites, 87;
achondrites, 5; irons, 7; stony-irons 1. These per-
centages agree remarkably well with those for all
recorded meteorite falls; the 809 confirmed falls
listed by Hutchison, et al. (1977) give the follow-
ing percentages: chondrites, 85; achondrites, 8;
irons, 6; stony-irons, 1. Thus the Allan Hills
collection appears to be a representative sampling
of the terrestrial meteorite flux. It is interesting
that iron meteorites are present in their statistical
proportion, although it might be expected that
they would sink to the bottom of the icecap
because of the great density difference between
nickel-iron and ice, and never be returned to the
surface. So far no evidence has been found to
support the suggestion by some researchers (e.g.,
Huss, 1977) that a percentage of meteorites may
go unrecognized because their composition is ter-
restrial or at least nonmeteoritic in our current
understanding. Certainly no apparently "non-
meteoritic" rocks have been found bearing a fu-
sion crust.
The statistical comparison can be extended to
the major classes of the most abundant group, the
chondrites. For the 81 classified chondrites in the
Allan Hills collection, the following percentages
are obtained: L, 48; H, 45; LL, 5; C, 2; E, 0. For
the 643 classified chondrites listed by Hutchison,
et al. (1977), the percentages are as follows: L, 45;
H, 40; LL, 8; C, 5; E, 2. The E (enstatite), C, and
LL chondrites appear to be somewhat under-
represented in the Allan Hills collection; for the
C (carbonaceous) chondrites this is understanda-
ble, since many of them are very friable and
would disintegrate rapidly even in the Antarctic
climate.
Terrestrial Ages
J. C. Evans and L. A. Rancitelli
Approximate terrestrial ages have been mea-
sured on 27 Antarctic meteorite specimens by
nondestructive gamma ray analysis of their 26A1
contents (Evans, Rancitelli, and Reeves, 1979).
The specimens include 20 chondrites collected
from the Allan Hills region in the 1977-78 season,
4 chondrites and 1 achondrite collected from the
Allan Hills in 1976-77, a chondrite from the
Yamato Mountains, and the chondrite discovered
in Adelie Land in 1912 by the Mawson Expedi-
tion. The 26A1 contents of these samples are com-
pared with expected saturation values established
by measurements on ordinary chondrites from 14
finds and 22 contemporary falls (Table 2). Several
of the Antarctic meteorites have also been ana-
lyzed for 36C1, 53Mn, and 21Ne (Table 3).
The calculated terrestrial residence times for
the 27 specimens range from less than 0.1 to
about 0.7 million years (Table 2). These include
the oldest terrestrial ages ever measured on chon-
drites. When compared with the contemporary
find and falls, the Antarctic specimens show a
perceptible shift toward lower 26A1 values and
hence older terrestrial ages (Figures 38, 39). The
26Al values also show a bimodal distribution in
which 11 of the 12 H-type chondrites have ap-
parent terrestrial ages of less than 300,000 years,
and 8 of the 12 L-type chondrites have estimated
terrestrial ages of more than 400,000 years. The
three oldest finds, with ages approaching 700,000
years, include an L3, an L5, and an L6 chondrite.
TABLE 2.?26A1 content of Antarctic meteorites
(expected saturation value: L = 59 ? 9, H = 55 ?
Meteorite
ALLAN HILLS
(ALHA)
76004
76005
76006
76007
76008
77002,9
77003,7
77014,5
77015,5
77025
77062
77071
77081
77086
77115,4
77118
77124
77140,7
77144
77150
77164
77167,3
77214,12
77272,7
77299,13
ADELIE LAND
USNM 2318
YAMATO MTS
7301(J)
Class
LL3
Eu
H6
L6
H6
L5
H3
H5
L3
H5
H5
H5
H?
H5
H5
H5
L3
H6
L6
L3
L3
L3
L6
H3
L5
H4
Weight
counted
(g)
52.5
337
271
78.5
281.3
73.4
272.4
137.2
131.8
18.7
16.3
10.5
8.4
18.7
137.5
7.6
4.1
30.8
7.6
57.9
38.0
184.6
758.6
272.1
106.7
64
521
26 AI/It
(dpm/kg)
58 ? 2
89 ? 2
51 ? 1
45 ? 1
11.2 ?0.4
30 ? 3
45 ? 5
55 ? 3
36 ?4
54 ? 5
47 ? 5
55 ?6
42 ?4
58 ? 6
48 ?3
53 ? 5
70 ? 7
40 ? 4
56 ?6
43 ? 4
44 ? 5
37 ? 2
56 ?6
35 ? 4
43 ? 4
50 ? 2
26 ? 3
Terrestrial
ape
o
(my)
<0.2
<0.1
<0.2
<0.4
<0.1
<0.7 ? 0.2
<0.5
<0.2
<0.7
<0.2
<0.3
<0.2
<0.5
<0.1
<0.4
<0.2
<0.1
<0.6
<0.2
<0.5
<0.5
<0.6
<0.2
<0.7
<0.4
<0.3
<0.1
J.C. Evans and L.A. Rancitelli, Physical Sciences Department,
Battelle-Northwest, Richland, Washington 99352.
Two specimens, ALHA76008 and ALHA-
77002, which were suspected on the basis of their
45
46
TABLE 3.?Class and 36C1, 53Mn, and 21Ne content
of Antarctic meteorites
Meteorite
ALHA 76008
ALHA 77002
Yamato 7301(J)
Class
H6
L5
H4
36Cl*
(dpm/kg
Fe)
9.6 ? 0.6a
4.7 ? l.la
18 ? la
53Mn*
(dpm/kg
Fe)
22 ? 5C
104 ? 6b
21 Ne
exposure
age (my)
1.5e
13d
* Expected saturation value: 36C1 = 24.5 ? 3.6f; 53Mn = 450 ?
90b.
References: a Nishiizumi, personal communication; Nishi-
izumi, 1978; c Nishiizumi, Imamura, and Honda, 1979; Takaoka
and Nagao, 1978; e Fireman, Rancitelli, and Kirsten, 1979; fBe-
gemann and Vilcsek, 1968.
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
low 26A1 contents of having terrestrial ages of 1
million years or more, proved to have 36C1 con-
tents indicative of short residence times (Table
3). In both cases, the data are interpreted as
reflecting a two-stage history of cosmic ray bom-
bardment involving a fairly recent breakup in
space of a body to its pre-atmospheric size, fol-
lowed by a short terrestrial residence time. The
Yamato chondrite, 7301 (J), appears to have had
a similar history.
8
on
LLJ
< 0
u_
o 4
ANTARCTIC (26 METEORITES)
(Z)
V\ i V7,
80
Al (dpm/kg)
FIGURE 38.?26A1 content of H- and L-type chondrites nor-
malized to L-type composition.
0
Ol)AI (dpm/kg)
FIGURE 39.? 6A1 content of Allan Hills chondrites by class
normalized to L-type composition.
The old terrestrial ages of Antarctic chondrites
have introduced a new and exciting element, not
only into meteorite research but, for the first time,
have provided the possibility of utilizing meteor-
ites as time probes of a terrestrial process. Mea-
surements of isotope pairs should make it possible
to span a range of terrestrial ages extending from
the present back 15 million years to the middle
Miocene when the Antarctic icecap is believed to
have been approximately its present size, but was
soon to undergo a significant expansion (Shack-
leton and Kennett, 1975). The large concentra-
tions of meteorites found on two sides of the
continent could well yield specimens old enough
to give new information on the age and motion
of portions of the Antarctic icecap.
Appendix 1
Characterized Meteorites from the 1977-78 Allan Hills
Collection
(listed in numerical sequence)
Class and type: A = achondrite, unique; C = carbonaceous chondrite; Di =
diogenite; Eu = eucrite; H = high-iron chondrite; L = low-iron chondrite;
LL = low-iron low-metal chondrite; M = mesosiderite; Ur = ureilite. Type
is indicated by the digit following the letter.
Olivine composition in mole percent Fe2SiC>4 (Fa).
Pyroxene (orthopyroxene or low-Ca clinopyroxene) composition in mole per-
cent FeSiO3 (Fs).
Degree of weathering: A = minor; metal flecks have inconspicuous rust halos,
oxide stain along cracks is minor. B = moderate; metal flecks show large
rust halos, internal cracks show extensive oxide stain. C = severe; specimen
is uniformly stained brown, no metal survives.
ALHA
number
77001
77002
77003
77004
77005
77014
77015
77021
77025
77033
77061
77062
77064
77071
77074
77081
77086
77088
77102
77118
77119
77124
77140
77144
77148
77150
77155
Weight
(grams)
252
235
780
2230
483
309
411
16.7
19.4
9.3
12.6
16.7
6.5
10.9
12.1
8.6
19.4
51.2
12.3
7.8
6.4
4.4
78.6
7.9
13.1
58.3
305
Class &
type
L6
L5
H3
H4
A
H5
L3
H5
H5
L3
H5
H5
H5
H5
H5
H?
H5
H5
H5
H5
H5
H5
L3
H6
H6
L6
L6
%Fa
in
oli-
vine
25
25
4-48
17-20
28
18
1-21
18
18
8-38
18
18
18
18
18
11
19
19
19
19
18
19
8-44
19
18
25
24
%Fs
in
pyrox-
ene
21
22
2-25
15-27
23
17
4-24
17
17
8-9
17
17
17
17
17
11
17
17
15
17
17
16
2-17
17
16
22
20
Degree
of
weather-
ing
B
B
A
C
A
C
C
C
C
C
B
B
B
B
B
B
C
C
B
C
C
C
C
B
C
C
A/B
ALHA
number
77160
77164
77165
77167
77177
77182
77190
77191
77192
77208
77214
77215
77216
77217
77219
77224
77230
77231
77233
77249
77250
77252
77254
77255
77256
77257
77258
Weight
(grams)
70.4
38.1
30.5
611
368
1109
387
642
845
1733
2097
820
1470
413
637
787
2473
9270
4087
504
10555
343
246
765
676
1996
597
Class &
type
L3
L3
L3
L3
H5
" H5
H4
H4
H4
H4
L3
L4
L4
L4
M
H4
L4
L6
H4
L3
iron
L4
L5
iron
Di
Ur
H6
%Fa
in
oli-
vine
3-46
6-39
8-33
2-41
18
19
17-19
16-18
16-18
17
1-49
22-26
23-26
17-25
26
19
22-25
24
14-21
7-35
22-28
23
9-23
18
%Fs
in
pyrox-
ene
6-40
3-41
6-35
3-17
16
17
15-22
14-16
15-21
14
4-23
9-21
10-19
9-26
24-28
17
18-29
21
15-17
2-25
2-22
20
23
12
16
Degree
of
weather-
ing
C
C
cc
cB
C
C
C
C
C
B
A/B
B
B
G
B
A/B
C
G
B
A/B
A/B
A
B/G
47
ALHA
number
77260
77261
77262
77263
77264
77269
77270
77271
77272
77273
77277
77278
77280
77281
77282
77283
Weight
(grams)
744
412
862
1669
11.0
1045
589
610
674
492
143
313
3226
1231
4127
10510
Class &
type
L3
L6
H4
iron
H5
L6
L6
H6
L6
L6
L6
LL3
L6
L6
L6
iron
%Fa
in
oli-
vine
7-23
24
15-19
19
24
24
18
24
24
24
11-29
24
24
24
%Fs
in
pyrox-
ene
1-28
2\
13-16
16
22
21
16
20
20
20
9-21
21
20
20
Degree
of
weather-
ing
C
B
B
A/B
B
A/B
A
B/C
B
A/B
A
B
B
B
ALHA
number
77284
77285
77288
77289
77290
77294
77296
77297
77299
77300
77302
77304
77305
77306
77307
Weight
(grams)
376
271
1880
2186
3784
1351
963
952
261
235
236
650
940
19.9
181
Class &
type
L6
H6
H6
iron
iron
H5
L6
L6
H3
H5
Eu
LL3
L6
C2
G3
%Fa
in
oli-
vine
25
18
19
17
24
24
11-21
18-19
18-27
24
1-30
%Fs
in
pyrox-
ene
21
16
17
15
21
20
15-20
15-17
37-64
13-19
21
1-12
Degree
of
weather-
ing
A/B
C
B
A
A/B
A
A
C
A
B
B/C
A
A
Appendix 2
Chemical Analyses of Some Allan Hills Meteorites
(E. Jarosewich, Department of Mineral Sciences, National Museum of
Natural History, Smithsonian Institution, Washington, D. C.)
Constituent
Fe
Ni
Co
FeS
SiO2
TiO2
A12O3
Cr2O3
FeO
MnO
MgO
CaO
Na2O
K2O
P2O5
H2O(+)
H2O(-)
C
Total
Total Fe
77003
4.50
1.37
0.07
4.85
34.19
0.14
2.89
0.49
21.78*
0.31
23.53
2.22
0.56
0.06
0.23
1.01
0.88
0.28
99.36
24.51
77005
n.d.
0.01
<0.01
<0.1
42.40
0.46
3.14
1.05
19.85
0.46
28.16
3.39
0.48
0.04
0.41
n.d.
0.02
0.02
99.89
15.43
77214
2.02
1.18
0.06
5.73
37.73
0.11
2.30
0.49
19.63*
0.33
22.69
1.70
0.82
0.07
0.21
2.34
0.95
1.08
99.44
20.77
77219
23.63
2.86
0.10
1.10
32.27
0.16
3.93
0.63
15.84*
0.41
12.56
3.14
0.15
0.03
0.30
1.02
0.61
0.15
98.89
36.64
77256
n.d.
0.01
<0.01
0.15
52.15
0.16
1.56
1.06
16.07
0.47
26.48
1.50
0.04
0.01
0.01
n.d.
0.02
0.03
99.72
12.49
77257
n.d.
0.08
<0.01
<0.01
41.12
0.04
<0.1
0.70
13.57
0.38
39.66
1.07
0.03
0.01
0.06
n.d.
0.18
3.34
100.24
10.55
77278
2.23
1.03
0.05
6.17
41.03
0.12
2.26
0.50
16.79*
0.34
24.08
1.90
0.82
0.10
0.20
1.20
0.38
0.16
99.36
19.20
77299
12.26
1.67
0.08
5.23
35.94
0.11
2.27
0.41
13.15*
0.30
22.50
1.81
1.08
0.12
0.22
1.15
0.56
0.38
99.24
25.80
n.d. = not determined.
* Weathered meteorite in which all FeO and Fe2O3 is reported as FeO.
Literature Cited
Begemann, F., and E. Vilcsek
1968. Chlorine-36 and Argon-39 Production Rates in
the Metal of Stone and Stony-Iron Meteorites. In
P. M. Millman, editor, Meteorite Research, pages
355-362. Dordrecht, Holland: D. Reidel Publish-
ing Company. '
Cassidy, W. A.
1977. Antarctic Search for Meteorites. Antarctic Journal,
12(4): 96-98.
1979. Antarctic Meteorites. EOS, 60:175-177.
Cassidy, W. A., E. Olsen, and K. Yanai
1977. Antarctica: A Deep-Freeze Storehouse for Mete-
orites. Science, 198:727-731.
Christophe Michel-Levy, M., and J. C. Lorin
1978. El Quemado, a New Type of Stone Meteorite
Fallen near Acapulco. Meteoritics, 13:411-412.
Evans, J. C, L. A. Rancitelli, and J. H. Reeves
1979. 26 Al Content of Antarctic Meteorites: Implica-
tions for Terrestrial Ages and Bombardment His-
tory. Proceedings of the Tenth Lunar and Planetary
Science Conference, pages 1061-1072. New York: Per-
gamon Press.
Fireman, E. L., L. A. Rancitelli, and T. Kirsten
1979. Terrestrial Ages of Four Allan Hills Meteorites:
Consequences for Antarctic Ice. Science, 203:453-
455.
Huss, G. I.
1977. Significance of the Yamato Meteorites. Meteoritics,
12:141-144.
Hutchison, R., A. W. R. Bevan, and J. M. Hall
1977. Appendix to the Catalogue of Meteorites. 297 pages.
London: British Museum (Natural History).
Kirsten, T., D. Ries, and E. L. Fireman
1978. Exposure and Terrestrial Ages of Four Allan Hills
Antarctic Meteorites. Meteoritics, 13:519-522.
Matsumoto, Y.
1978. Collection of Yamato Meteorites, East Antarctica
in November and December 1975, and January
1976. Memoirs of the National Institute of Polar Research
(Japan), special issue, 8:38-50.
McSween, H. Y. Jr., L. A. Taylor, and E. M. Stolper
1979. Allan Hills 77005: A New Meteorite Type Found
in Antarctica. Science, 204:1201-1203.
Miyamoto, M., H. Takeda, and K. Yanai
1979. Eucritic Polymict Breccias from Allan Hills and
Yamato Mountains, Antarctica. Lunar and Planetary
Science X, pages 847-849. Houston: Lunar and
Planetary Institute.
Nishiizumi, K.
1978. Cosmic Ray Produced 53Mn in Thirty-one Mete-
orites. Earth and. Planetary Science Letters, 41:91-100.
Nishiizumi, K., M. Imamura, and M. Honda
1979. Cosmic Ray Produced Radionuclides in Antarctic
Meteorites. Memoirs of the National Institute of Polar
Research (Japan), special issue, 12:161-177.
Olsen, E. J., A. Noonan, K. Fredriksson, E. Jarosewich, and
G. Moreland
1978. Eleven New Meteorites from Antarctica, 1976-
1977. Meteoritics, 13:209-225.
Shackleton, J. J., and J. P. Kennett
1975. Late Cenozoic Oxygen and Carbon Isotopic
Changes at DSDP Site 284: Implications for Gla-
cial History of the Northern Hemisphere and Ant-
arctica. In S. M. White, editor, Initial Reports of the
Deep Sea Drilling Project XXIX, pages 801-807.
Washington, D.C.: National Science Foundation.
Shima, M., and M. Shima
1973. Mineralogical and Chemical Composition of New
Antarctic Meteorites. Meteoritics, 8:439-440.
Shiraishi, K., R. Naruse, and K. Kusonoke
1976. Collection of Yamato Meteorites, Antarctica in
December, 1973. Antarctic Record, 55:49-60.
Takaoka, N., and K. Nagao
1978. Rare Gas Studies of Yamato-7301, 7305, and 7304.
Memoirs of the National Institute of Polar Research
(Japan), special issue, 8:198-208.
Takeda, H., and M. Miyamoto, M. B. Duke, and K. Yanai
1978. The Yamato-74659 Ureilite and Some New Find-
ings on the Yamato Achondritic Pyroxenes. Meteo-
ritics, 13:641-645.
Van Schmus, W. R., and J. A. Wood
1967. A Chemical-Petrologic Classification for the
Chondritic Meteorites. Geochimica et Cosmochimica
Ada, 31:737-765.
Weber, H. W., and L. Schultz
1978. Noble Gases in 10 Stony Meteorites from Antarc-
tica and Their Exposure Ages. Meteoritics, 13:658-
660.
Yanai, K.
1976. Search and Collection of Yamato Meteorites, Ant-
arctica, in October and November, 1974. Antarctic
Record, 56:70-81.
1978. First Meteorites Found in Victoria Land, Antarc-
tica, December 1976 and January 1977. Memoirs of
the National Institute of Polar Research (Japan), special
issue, 8:51-69.
49
50 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES
Yanai, K., W. A. Cassidy, M. Funaki, and B. P. Glass Based on the Chemical Compositions of Their
1978. Meteorite Recoveries in Antarctica during Field Olivines and Pyroxenes. Memoirs of the National
Season 1977-78. Proceedings of the Ninth Lunar and Institute of Polar Research (Japan), special issue, 8:
Planetary Science Conference, pages 977-988. New 110-120.
York: Pergamon Press. Yoshida, M., H. Ando, K. Omoto, R. Naruse, and Y. Ageta
Yanai, K., M. Miyamoto, and H. Takeda 1971. Discovery of Meteorites near Yamato Mountains,
1978. A Classification for the Yamato-74 Chondrites East Antarctica. Antarctic Record, 39:62-65.