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Elephant Moraine A79001
Basic information Name: Elephant Moraine A79001
     This is an OFFICIAL meteorite name.
Abbreviation: EETA79001
This meteorite may also be called Elephant Moraine 79001 (EET 79001) in publications.

Observed fall: No
Year found: 1979 or 1980
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 7.94 kg
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 3(3)  (1980)  Shergottite
Meteoritical Bulletin:  MB 76  (1994)  Shergottite
NHM Catalogue:  5th Edition  (2000)  Martian (shergottite)
MetBase:  v. 7.1  (2006)  Shergottite-basaltic (ol phyric)
Recommended:  Martian (shergottite)    [explanation]

This is 1 of 170 approved meteorites (plus 1 unapproved name) classified as Martian (shergottite).   [show all]
Search for other: Martian meteorites
Writeuphelp
Writeup from AMN 3(3):
This text was reprinted from AMN 3(3) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: EETA79001

Location: Elephant Moraine

Field No.: 1043

Weight (gms): 7942.0

Meteorite Type: Shergottite

 

Physical Description: Roberta Score

All but one surface of this achondrite (22 x 17 x 14 cm.) is covered with black fusion crust, but there are areas on all surfaces where the fusion crust has been plucked away. One surface has a deep regmaglypt that is covered with fusion crust. The areas devoid of fusion crust are white-gray in color and the matrix appears porous. Veins (~0.5 mm wide) of dark material criss-cross each other. Whitish-yellow clasts (~3mm diameter) are scattered all over this achondrite. Most of the specimen appears very fine-grained but a small part near the E surface has a different lithology. Sawing this meteorite exposed a light colored interior with rounded white clasts, as large as 0.5 cm in diameter. Several large black fine-grained clasts as large as 2.5 cm are scattered over the cut face. Some of these black clasts contain glass lined vugs. Upon chipping one of these clasts containing a vug, the entire clast popped out easily with no matrix adhering to the clasts. Numerous veins of black material criss-cross each other. Most of these veins run through a black clast. The longest vein is 14 cm long. Near the W end of the cut face are brownish colored clasts which may or may not be pyroxene. 90% of the cut face is fine-grained. 10% (near the E end) of the cut face consists of intergrown pyroxene and feldspar in a basaltic texture.

 

Petrographic Description: Arch Reid

Thin sections were cut from the three different lithologies: 1) the main mass of the meteorite; 2) the material with basaltic texture that is present at one end of the sample, and; 3) the dark clasts included in the main mass.

 

The main mass is a shocked but unbrecciated pyroxenite with pyroxene as the major phase but also containing maskelynite, Mg-Al chromite, iron sulphide and ilmenite(?). The major pyroxene is polysynthetically twinned pigeonite (?) (resembling twinned clinobronzite) ranging in composition from WosEn70Fs25 to Wo12En50Fs38. Orthopyroxene forms the cores of larger pyroxene grains and ranges in composition from Wo1.5En83Fs16 to Wo3En78Fs19. The larger pyroxenes grains, up to 3.5 mm, comprise untwinned cores zoned outward to polysynthetically twinned rims. The smaller pyroxenes, .3 to 1 mm, are twinned clinopyroxenes and are intergrown with maskelynite laths. The maskelynite ranges in composition from Or1Ab39An60 to Or1.5Ab44An55. A few large olivines, Fo77to Fo73 range up to 2.5 mm.

 

The less abundant lithology closely resembles Shergotty in texture but is finer grained. The major minerals are clinopyroxene and maskelynite: calcium phosphate, SiO2, ilmenite (?) and magnetite (?) are also present. Elongate clinopyroxene and laths of maskelynite are about one mm long and generally subparallel: many of the maskelynite grains contain pyroxene inclusions. Analysed pigeonites range from Wo10En52Fs38 to Wo19En15Fs67. The maskelynite also shows a range in composition from Or.5Ab38An62 to Or4Ab50An46.

 

The dark clasts are apparently loci of melting; in many cases they connect with the thin black glassy (?) veinlets that traverse much of the meteorite. Thin sections from these dark areas show glass (with relict olivine, pyroxene and maskelynite inclusions), devitrified glass, areas with mosaic texture and vesicular areas with quench textures. The dark areas appear to be more common in olivine-bearing portions of the main mass.

 

The meteorite is classed as a shergottite because of the close similarities to the shergottites in texture and mineralogy. Both lithologies however are distinct from Shergotty and Zagami.

Data from:
  MB76
  Table 2
  Line 1438:
Origin or pseudonym:Main icefield
Mass (g):7942
Class:Sherg
Weathering grade:Ae
Fayalite (mol%):23-27
Ferrosilite (mol%):16-67
Comments:26Al=23±3
Catalogs:
Search for specimens in the Smithsonian Institution collection (U.S.):   
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References: Published in Antarctic Meteorite Newsletter 3(3) (1980), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
Find references in NASA ADS:
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Photos:
CreditPhotos
Photos from the Encyclopedia of Meteorites:
Dr Carlton Allen, JSC-KT, NASA         
Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (76° 11'S, 157° 10'E)
     Recommended::   (76° 17' 27"S, 157° 16' 0"E)
Note: the NHM and MetBase coordinates are 12.3 km apart

Statistics:
     This is 1 of 38180 approved meteorites from Antarctica (plus 5051 unapproved names)
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