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 Meteorites, 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 contamination, 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 numerical 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

i n
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 elsewhere. 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 independently planned a similar proposal. As a result, in

1976-77 the NSF Division of Polar Programs

supported a joint expedition by Cassidy and Olsen, 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, Smithsonian 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 Mountains 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 unexpected windfall of extraterrestrial material.

Cassidy initiated these discussions at the annual

meeting of the Meteoritical Society in Cambridge, England, in July 1977. In November 1977,

the NSF convened an ad hoc committee of representatives from the NSF, the National Aeronautics and Space Administration (NASA), the

Smithsonian Institution (SI), and the scientific

community. As a result of this committee meeting, a plan was drawn up for the collection,

processing, and distribution of Antarctic meteorites collected during the 1977-78 field season.

This plan provided for the meteorites to be collected and returned to the United States, as far

as possible in their pristine condition (in continuously 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 committee 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 members, representing the field collection teams, the

curation groups, and members of the scientific

community. Its primary responsibility is to consider 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 members, one each from NSF, NASA, and SI. Its

function is to review the recommendations of the

MWG, transmit them to the appropriate authorities, 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 Newsletter 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 samples 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 scientists 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 independently 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 research, if required, must be submitted separately

to the appropriate funding agencies.

Sample requests should provide detailed scientific justification of the proposed research. Requests for specific samples should include sample

numbers, weight requirements, and special handling and shipping requirements. Consortiumtype 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, Washington, D.C. (contact Brian Mason, Curator),

and at the National Institute of Polar Research,

Ministry of Education, 1-9-10, Itabashi-ku, Tokyo, 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 specimens, 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 distinct 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 mechanism 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, University 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, submitted in May 1974, was to search for meteorites

during field season 1975-76 on ice patches accessible 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 meteorites 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 cooperative 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 Olsen of the Field Museum of Natural History,

Chicago, and myself.

Yanai had a valuable store of previous Antarctic experience and had been heavily involved in

the Yamato Mountains meteorite recoveries. Olsen had earlier been in Greenland. Therefore, I

was the only member of the group without previous 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 meteorites. 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 helicopter 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 another one about 700 m away. Olsen, Yanai, and

FIGURE 1.—Meteorite fragment found near Mt. Baldr. Eddycurrent 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 helicopter 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, followed 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. Subsequently we investigated a number of areas of bare

ice located where the ice plateau meets the

Transantarctic Range, but found nothing. During the closing days of the field season, acting at

the suggestion of Ken Craper, one of the helicopter 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. Accounts 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, lowlevel observing platform, from which we could

scan large areas in a short time. We found also

that our helicopter pilots quickly gained proficiency not only in spotting rocks from about 10

meters above the ice surface but also in differentiating between rocks and meteorites. Thus we

owe many of these finds and many subsequent

discoveries to the excellent U.S. Navy flight personnel assigned to support the U.S. research effort.

The 1976-77 discoveries (Figure 3) demonstrated 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 previously undescribed meteorite types and also, possibly, lunar rocks that had reached the earth as

1

 (\

90* W

^SiM C 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 collecting 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 meteorites should be handled. The response (Cassidy,

1979) included both specific and general suggestions 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 National 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 Houston. My co-investigator for the 1977-78 field

season was Billy Glass of the Geology Department, 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 content, 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 Manhaul 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 concentration. 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 conditions for very long periods of time and weathering

of rocks proceeds very slowly, so that concentrations 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 Purgatory 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 environment.

The Allan Hills concentration is another matter

(Figure 4). Through field season 1977-78 we had

recovered about 350 specimens, representing perhaps 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 moving 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 monocline within an area of about 100 square kilometers. 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 northern 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 penetrated 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, Antarctica, in the 1977-1978 field season were packaged

in specially prepared containers and were returned to the Curatorial Facility of the NASA

Johnson Space Center (JSC) at temperatures

below 0°C (Figure 6a). The meteorites were unpacked, photographed, and processed at the Curatorial Facility by procedures that drew on experience gained from the processing of lunar samples. 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, aluminum 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 chondrites 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 meteorites 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 meteorites were unpacked and placed inside a cold

storage room at —40°C. Ice placed in one of the

boxes in Antarctica was unmelted, which indicates 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 meteorites with their field photographs and to deter-
NUMBER 23

mine their orientation on the ice. Processing numbers initially assigned to the specimens were

30001 to 30307. These were later replaced by the

permanent name/number combinations recommended 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 threedigit 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 referred to in the catalog, the first specimen in

the collection bears the identification: ALHA77001, XX, where the digits following the comma

refer to subsamples taken from this meteorite

specimen.

The initial processing of meteorites in the Curatorial Facility provided a rapid characterization

of each specimen that was reported to the meteoritical 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, described, 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 atmosphere, 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 degradation 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 nitrogen onto its underside. The meteorite was

always returned to this cold plate between operations, 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 summary of the initial processing steps in their approximate 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 (orthogonals 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 longterm 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 (Figure 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 atmosphere; no coolants are used.

Division of Meteorites in Washington, where scientists 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 manner. These meteorites were allowed to thaw overnight 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 4X 5 inch negatives. The six

orthogonal views taken of the larger meteorites

record many details of the surface features (ablation 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 relative orientation of the specimens as assigned during 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, stainless 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 Foundation and the National Institute of Polar Research 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 cabinet. Allocations for requested material were filled

by chipping off appropriate samples with a chisel.

Attempts were made to obtain samples according to specific requirements of investigators.

Chipping rather than sawing was used as much

as was practical, to minimize possible contamination. In the case of the achondrites, several

grams of interior material were crushed to provide

representative samples to investigators performing 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 investigator could extract his own samples. Most polished thin sections allocated to investigators were

made in the thin-section laboratory of the Curatorial 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 individual 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 descriptions follow the order of increasing petrographic type. The descriptions are based largely

on those published in the Antarctic Meteorite

Newsletter, with additional information as available. The letter-number designation for each meteorite concurs with guidelines recommended by

the Committee on Nomenclature of the Meteoritical Society; it carries the following information: 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 Research, 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, NorthropHouston, 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 polished 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 nearsurface weathered material probably close to the

fusion crust. In a few instances, more complete

examination and consideration of possible pairings 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). ACHONDKiTES.—Eucrites: ALHA76005 (1425 g), 77302

(236 g). Diogenite: ALHA77256 (676 g). Ureilite:

ALHA77257 (1996 g). Unique: ALHA77005

(483 g). STONY-IRONS.—Mesosiderite: ALHA77219 (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 furrowed. 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 scattered throughout. No obvious chondrules are visible 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 defined chondrules up to 0.5 mm in diameter; most

consist largely of granular olivine and some contain 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 consists largely of a layer-lattice silicate, which by

analogy with other C2 meteorites can be tentatively identified as as ferruginous chlorite. Scattered 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 meteorite 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 characterized 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 Xray 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 fusion 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 approximately 1X 2 cm where the interior is exposed.

Abundant small (~1 mm) metallic flecks, chondrules, 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 polysynthetically twinned clinopyroxene; some chondrules have pale brown transparent glass interstitial to the olivine and pyroxene grains. Microprobe analyses show that both olivine and pyroxene 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 tentatively classified L3 in the preliminary examination) .

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 diameter) and irregular crystalline aggregates with interstitial nickel-iron and troilite and a small

amount of matrix. A considerable variety of chondrules 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 meteorite 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 charcoalbrown 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 observed 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 present. 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; transparent 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 chondrule margins; the nickel-iron grains are corroded

extensively and altered to limonite, and thin veins

of limonite occur throughout the section. Microprobe analyses show a wide range in the composition of olivine (Fai-Fa2i) and pyroxene (Fs4-

FS24); the pyroxene is a low-calcium clinopyroxene (CaO = 0.2% to 0.5%). This range of com4 *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 angular, 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 polysynthetically twinned clinopyroxene, porphyritic olivine, and fine-grained pyroxene. Some chondrules 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 pyroxene 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 fragments (?) 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 present on this stone.

The polished thin section (Figure 12a) shows

an elliptical nonchondritic enclave (8X 5 mm),

completely enclosed in chondritic material. The

enclave consists of polysynthetically twinned

clinoenstatite (with a range of composition, averaging Woo.2Fs7En93) poikilitically enclosing irregular 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 consists 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 clinopyroxene, 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 composition of olivine and pyroxene indicates a type 3

chondrite, and the mean composition of the olivine 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 petrography that they are described together; they may

be different pieces of the same meteorite. Although 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 specimens 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 chondrules 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. Interstitial glass in chondrules is pale gray, transparent to turbid. Minor subequal amounts of

troilite and nickel-iron are present, the nickel-iron

is extensively altered to red-brown limonitic material, 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 suggests L group; these meteorites, therefore, are

classified L3 chondrites.

ALHA77167 (611 g).—This is an angular specimen (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 lightcolored angular clasts and chondrules, as much

as 0.5 cm in diameter, are apparent through the

weathering rind. Many small holes are distributed 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 finegrained matrix. The chondrules range from 0.2

FIGURE 13.—ALHA77167, L3 chondrite; a deeply fractured

stone with a pitted surface, probably produced by the weathering 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 polysynthetically twinned clinopyroxene. The granular

chondrules contain intergranular glass, mostly

turbid and partly devitrified, but rarely transparent 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 numerous 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-calcium (CaO = 0.2% to 0.5%). This range of composition, 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 fracture plane. The stone contains many fissures. The

material near these is severely weathered and

friable. Snow was observed in several of the fissures 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 surface. 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 chondrules 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 distinguish because of the weathering. Microprobe

analyses show a wide range in olivine composition, Fai-Fa49. The section contains an elliptical

body 3 mm across (a chondrule or a lithic fragment) with a poikilitic texture of orthopyroxene

(\V01Fs13En86) enclosing smaller round grains of

olivine Fai7-2o, averaging Fai8 and another pyroxene (?) (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, portions 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 inclusions 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 exterior surface.

The thin section shows an aggregate of welldefined 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 chondrules commonly have interstitial glass, mostly

turbid and partly devitrified, but rarely transparent and pale brown. Pyroxene grains show polysynthetic twinning. Sparse nickel-iron and troilite

are concentrated on the surfaces of chondrules.

Limonitic staining pervades the section, and scattered grains of reddish brown limonite are present. 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 suggests L group; the meteorite, therefore, is tentatively 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 penetrate 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 chondrules are irregular or broken. A variety of chondrule 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 pyroxene is polysynthetically twinned clinopyroxene.

The groundmass is fine-grained olivine and pyroxene, with minor subequal amounts of nickeliron 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 pyroxene 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 collected by the 1976-77 party. Olsen, et al. (1978:

214-216) described it (as Allan Hills #4) as follows:

[It] is a very heterogeneous breccia consisting of chondrules

and chondrule fragments, clasts of several different crystalline 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 LLgroup 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, chromite, and other spinel-group phases.

ALHA77278 (313 g).—This is a moderately

rounded conical specimen (Figure 16), approximately 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). Approximately 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 weathered, but the matrix is not.

The polished thin section (Figure 1 la) shows a

FIGURE 17.—LL3 chondrites: a, ALHA77278, photomicrograph of thin section (width of field is 2.0 mm); the center

of the photograph is occupied by the carbonaceous (?) enclave 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 ellipsoidal chondrules (0.3-1.8 mm diameter) with interstitial nickel-iron and troilite (concentrated as

rims to chondrules) and relatively little matrix.

Most chondrules consist of granular or porphyritic olivine, commonly accompanied by polysynthetically twinned clinopyroxene, and with partially 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 pyroxene in a brown-black semitranslucent, possibly

carbonaceous matrix. Another, 3 mm long, consists 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 inclusions 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 finegrained 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 chondrules 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 composition; the olivine in the enclave has uniform

composition, Fa25. A few grains of calcic plagioclase, averaging An77, were noted. The low content of nickel-iron and troilite suggest LL group,

and the wide range of olivine and pyroxene compositions 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 weathFIGURE 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 approximately 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<:); however, the B surface is concave. This stone is extremely weathered, making it difficult to determine the amount of fusion crust present. The

oxidation staining is semiglossy and reddish

brown. Parallel fractures, in the north-south direction, penetrate the stone. No unweathered material 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 angular, 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 unweathered 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 specimen, 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 inclusions 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 evaporites, 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, chondrules averaging 0.5-1.0 mm in diameter.

(ALHA77233 has some unusually large chondrules, ranging up to 2.8 mm in diameter.) A

variety of chondrule types is present, the commonest being porphyritic to granular olivine,

barred olivine, fine-grained pyroxene, and granular 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 polysynthetically 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 distinguished 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 approximately 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 numerous 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 inclusions (rounded and irregular), ranging to more

than 2.0 cm in diameter, are apparent on the

fracture surfaces; these range from white to whitish 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 inclusions, 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 approximately 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 recently 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-developed 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 polysynthetically twinned clinopyroxene. Weathering is

slight, being confined to a small amount of limonitic staining around the nickel-iron grains.

Microprobe analyses show variability in olivine

and pyroxene compositions; olivine; Fai7-26, average 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 pyroxene 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, Photomicrograph 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, porphyritic olivine, and pyroxene that is either finegrained or polysynthetically twinned. Some chondrules have interstitial turbid devitrified glass.

Minor subequal amounts of troilite and nickeliron are present. A moderate amount of limonitic

staining pervades the section. Fusion crust is present on one edge of the section. Microprobe analyses show olivine (Fa22-25, average Fa23) and pyroxene (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 weathering 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 chondrules 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 compositions: olivine, Fa25; pyroxene, FS20. Minor plagioclase (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 specimens (Figure 23a) and are very similar in macroscopic and microscopic appearances and in degrees 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 apparent 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 meteorite 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 deposits, fills the grooves in the polygonal fractures

on the B surface. This surface appears more severely 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 fragments?), 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 deposit 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 unweathered 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 chondrites 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 (Fais19) and orthopyroxene (Fsi5_i7) are essentially uniform within the individual specimens.

The following specimens are possible pieces of

a single meteorite: ALHA77O21, 77025, 77061,

77062, 77064, 77071, 77074, 77086, 77088. Confirmation of these and possible additional groupings requires additional research.

CLASS L5

FIGURES 26, 27

ALHA 77002 (235 g).—The meteorite, approximately 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 dominantly 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; plagioclase 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 averages 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 weathering 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 slickensides. 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 olivine and olivine-pyroxene, and radiating pyroxene. The chondrules are set in a granular matrix

of olivine and orthopyroxene, with minor subequal amounts of nickel-iron and troilite. Limonitic 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 perform a bulk analysis The analysis is that of a normal Hgroup 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 contamination during the long weathering history.

Examination of a specimen and thin section of

ALHA76008 in the Smithsonian Institution (Mason, 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 collected by the 1977-78 party are far more weathered than76008, and might therefore be expected

to give very old terrestrial ages. However, weathering 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 unaffected. Caution should therefore be used in correlating degree of weathering with terrestrial age.

Kirsten, Ries, and Fireman (1978) have calculated 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 considerably weathered; yellow-brown limonitic staining pervades the thin sections.

ALHA77258 (597 g).—This five-sided specimen is completely covered with fusion crust, with

the exception of one small area. The matrix material is yellowish brown with small metallic particles.

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 missing, 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 meteorite 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 granular 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 uniform composition.

MBRA76001 (17881 g).—These two stones,

originally called "Mt. Baldr a and b," were collected 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 subsequent movement by the glacial tongue that ultimately avalanches 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 raregas 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 principal 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 (Figure 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 defined chondrules, which tend to merge with the

granular groundmass (Figure 30). Principal minerals are olivine and orthopyroxene in subequal

amounts, together with minor amounts of plagioclase, nickel-iron, troilite, diopside, and accessory

chromite and merillite. Microprobe analyses (Appendix 1) show essentially uniform compositions

for the principal minerals: olivine, Fa24-25; orthopyroxene, 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 weathered, 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 meteorite is an equigranular (grains 0.1-0.3 cm in

diameter) aggregate of approximately equal

amounts of olivine and orthopyroxene, with minor amounts of diopside, plagioclase, nickel-iron,

and troilite, and accessory chromite. Fusion crust

is present along one edge of the section. A moderate amount of yellowish brown limonitic stain

is present, concentrated around nickel-iron grains.

Microprobe analyses show the minerals are uniform in composition: olivine, Fan; orthopyroxene, 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 mineralogical composition is similar to that of the Hgroup chondrites, which suggests that this meteorite may be a completely recrystallized chondrite. 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 collected 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 macrocrystalline 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, plagioclases, oxide minerals, sulfides, and metal. In overall appearance it is very similar to some lunar breccias.

They also report (1978:220-221) pyroxene compositions 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 angular to subrounded with the approximate dimensions 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 section (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 protruding gabbroic clast, which is obviously coarser

grained and darker in color than the bulk meteorite. Plagioclase crystals in this clast are several

millimeters long. Another surface has an irregularly 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 pigeonite (~60%) as brown grains, up to 2 mm, and

plagioclase (~35%) as colorless grains, up to 4

mm, in a comminuted groundmass of these minFIGURE 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 weathering is visible. Microprobe analyses show a range

of compositions in the pigeonite: W03-14, En32_56,

Fs37_64; a few grains of subcalcic ferroaugite averaging W025 En27 FS48 were also analyzed. Plagioclase 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 pyroxene compositions of ALHA76005 and 77302 suggests 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 lacking 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 composition \V02Fs23En75. Some orthopyroxene grains

contain small blebs of clinopyroxene, with composition 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 staining 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, Photomicrograph 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 surfaces 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 undulose extinction. The pyroxene shows coarse

polysynthetic twinning. Grain boundaries are

marked by a concentration of carbonaceous material; 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 lowcalcium clinopyroxene with composition averaging \V07En8iFs12. The meteorite is extremely resistant 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 Appendix 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 partially 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, Wellrounded 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 orthopyroxene (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 apparently 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 heterogeneity 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 somewhat 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, commonly poikilitically enclosing olivine; some crystals show coarse polysynthetic twinning; the composition ranges somewhat, averaging \V05Fs23

En72. Maskelynite is present as laths interstitial to

olivine and pyroxene; it has labradorite composition (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 olivine is comparable in composition to that in

chassignites, the pyroxene to that in diogenites,

and the bulk composition will thus be intermediate 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 (12X8X 7 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 subangular inclusions up to 1 cm across are visible on

the weathered surface; these are probably pyroxene 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 orthopyroxene clasts and groundmass is somewhat variable, FS24-28, with CaO ranging from 0.5% to

2.3%; one grain of diopsidic pyroxene was analyzed, W043 En45 FS12. The major material of this

a

FIGURE 36.—ALHA77219, mesosiderite: a, Subangular pyroxene 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 comminuted 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 nickeliron 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, collected 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 troilite 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 southeast 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 probably represent burned-out troilite inclusions (residual 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 cemented 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 conditions 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 preferential 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 proximity 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 consideration 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 following percentages are obtained: chondrites, 87;

achondrites, 5; irons, 7; stony-irons 1. These percentages agree remarkably well with those for all

recorded meteorite falls; the 809 confirmed falls

listed by Hutchison, et al. (1977) give the following 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 terrestrial or at least nonmeteoritic in our current

understanding. Certainly no apparently "nonmeteoritic" rocks have been found bearing a fusion 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 underrepresented in the Allan Hills collection; for the

C (carbonaceous) chondrites this is understandable, 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 measured 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 Expedition. The

 26A1 contents of these samples are compared 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 analyzed 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 chondrites. 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 apparent 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 / I t

(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 ALHA77002, 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.l a

18 ± l a

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; Nishiizumi, 1978;

 c Nishiizumi, Imamura, and Honda, 1979; Takaoka

and Nagao, 1978;

 e Fireman, Rancitelli, and Kirsten, 1979; fBegemann 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 contents indicative of short residence times (Table

3). In both cases, the data are interpreted as

reflecting a two-stage history of cosmic ray bombardment involving a fairly recent breakup in

space of a body to its pre-atmospheric size, followed 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 normalized 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 meteorites as time probes of a terrestrial process. Measurements 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 (Shackleton and Kennett, 1975). The large concentrations 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 percent 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

olivine

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

pyroxene

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

weathering

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

olivine

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

pyroxene

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

weathering

C

C

c

c

c

B

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

olivine

7-23

24

15-19

19

24

24

18

24

24

24

11-29

24

24

24

%Fs

in

pyroxene

1-28

2\

13-16

16

22

21

16

20

20

20

9-21

21

20

20

Degree

of

weathering

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

olivine

25

18

19

17

24

24

11-21

18-19

18-27

24

1-30

%Fs

in

pyroxene

21

16

17

15

21

20

15-20

15-17

37-64

13-19

21

1-12

Degree

of

weathering

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.
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