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Lewis Cliff 85300
Basic information Name: Lewis Cliff 85300
     This is an OFFICIAL meteorite name.
Abbreviation: LEW 85300
Observed fall: No
Year found: 1985
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 210 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 9(3)  (1986)  Eucrite
AMN 17(1)  (1994)  Eucrite-pmict
Meteoritical Bulletin:  MB 76  (1994)  Eucrite-pmict
NHM Catalogue:  5th Edition  (2000)  Eucrite-pmict
MetBase:  v. 7.1  (2006)  Eucrite-pmict
Recommended:  Eucrite-pmict    [explanation]

This is 1 of 342 approved meteorites classified as Eucrite-pmict.   [show all]
Search for other: Achondrites, Eucrites, and HED achondrites
Comments: Field number: 2474
Writeuphelp
Writeup from AMN 9(3):

Sample No.: LEW85300, 85302, 85303

Location: Lewis Cliff

Weight (g): 210.3; 114.5; 408.0

Field Nos.: 2474; 2422; 2488

Dimensions (cm): 7x6.5x3.5; 5.5x5x3; 8.5x6x5.5

Meteorite Type: Eucrite

 

Macroscopic Description,: Roberta Score

Thin, shiny fusion crust with flow marks coats most of the top of LEW85300. The bottom surface has some fusion crust but most of this face is a fracture surface which appears to have been moderately polished. Fusion crust appears as dull patches on 85302 and 85303. Several large semi-rounded polymineralic clasts (as large as 2 x 2 cm in dimension) have sharply defined edges and are set in a black matrix that is made up of minute inclusions.

 

Cleaving the stones in half revealed an interior that is lighter in color than the exterior. Several different sharply defined clasts, including white, fine-grained clasts and black aphanitic clasts, were exposed. One large interior area shows extensive oxidation.

 

Thin Section (LEW85300,12; ,13; ,14) Description: James L. Gooding and Brian Mason

,12: A large ( 6 mm apparent maximum dimension) light-colored clast is enclosed by finer-grained dark matrix. Clast is composed of subhedral clinopyroxene and plagioclase (typical grain size is a few tenths mm) in a groundmass of granular pyroxene. Both clinopyroxene and plagioclase are cloudy and show crenulated and undulatory extinction under crossed polars. Some clinopyroxene crystals show very fine herringbone texture (probably exsolution lamellae). Ilmenite (?) is abundant in the clast and occurs as irregular grains of 0.01-0.2 mm size. Matrix surrounding clast is a porous, clastic aggregate of pyroxene and plagioclase mineral fragments with characteristic grain sizes of 0.1-0.2 mm, but with increasingly finer grains between the large grains. Other optical properties of pyroxene and plagioclase are similar to those described for the clast.

 

,13: Nearly all of exposed area is subophitic basalt that is comparable in grain size to the clast in ,12, but with much better preserved igneous texture. Clinopyroxene has pronounced herringbone texture (more abundant than in ,12) and ilmenite (?) is an accessory phase.

 

,14: At least two large clasts (~4-5 mm) of subophitic basalt (with ilmenite (?)) float in a finer-grained clastic matrix, as in ,12. At least two irregular grains of Ni-Fe metal (one ~0.015 mm, the other ~0.12 mm) occur, with the larger one being in the matrix and the smaller one in a clast. The most interesting feature of this section is a dark clast (~2-3 mm size) that resembles a fragment of carbonaceous chondrite (possibly C3). Most of this clast consists of an opaque matrix of low reflectivity (resembles reflectivity of magnetite) with a floating framework of cloudy, irregular, polymineralic clasts and isolated single-crystal mineral fragments. Some of the clasts are nearly spherical but resemble "inclusions" more than "chondrules"; olivine might exist in some of them. Both the border of this clast and objects within it are defined by haloes of dispersed, very fine-grained sulfides. One small grain of possible Ni-Fe metal was observed.

 

Microprobe analyses of the LEW85300,14 section (by B. Mason) show pyroxene compositions clustering around Wo3Fs60 and ranging to Wo43Fs26, with the mean of 15 analyses Wo12Fs52; two grains with composition Wo3Fs33 were found. Plagioclase ranges in composition An84-93 with a mean of An89. The dark clast is a fragment of a C3 carbonaceous chondrite, consisting largely of fine-grained olivine, ranging in composition Fa1-44; one grain of clinoenstatite (Fs5) and one of spinel (FeO 0.8%) were analysed. The meteorite is a eucrite with a C3 clast.

Data from:
  MB76
  Table 2
  Line 2876:
Origin or pseudonym:Upper Ice Tongue
Mass (g):210.3
Class:Eu "pm"
Weathering grade:A/B
Ferrosilite (mol%):32-63
Comments:NTL=19±4; 85300 pairing group
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 9(3) (1986), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (84° 17'S, 161° 5'E)
     Recommended::   (84° 17' 31"S, 161° 18' 48"E)
Note: the NHM and MetBase coordinates are 2.7 km apart

Statistics:
     This is 1 of 39175 approved meteorites from Antarctica (plus 5051 unapproved names)
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