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Lewis Cliff 85313
Basic information Name: Lewis Cliff 85313
     This is an OFFICIAL meteorite name.
Abbreviation: LEW 85313
Observed fall: No
Year found: 1985
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 191.2 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 9(3)  (1986)  Diogenite
AMN 11(1)  (1988)  Howardite
Meteoritical Bulletin:  MB 76  (1994)  Howardite
NHM Catalogue:  5th Edition  (2000)  Howardite
MetBase:  v. 7.1  (2006)  Howardite
Recommended:  Howardite    [explanation]

This is 1 of 383 approved meteorites classified as Howardite.   [show all]
Search for other: Achondrites, HED achondrites, and Howardites
Comments: Field number: 2498
Writeuphelp
Writeup from AMN 9(3):

Sample No.: LEW85313

Location: Lewis Cliff

Weight (g): 191.2

Field No.: 2498

Dimensions (cm): 8 x 5.5 x 4.5

Meteorite Type: Diogenite

 

Macroscopic Description: Roberta Score

Dull fusion crust covers most of LEW85313 except where large pieces of stone have been plucked out. This feature is abundant and makes this meteorite resemble a piece of Swiss cheese.

 

A brownish-gray weathering rind extends from less than 1 mm to greater than 1 cm into the interior. The massive gray matrix contains both rounded and irregular inclusions that range in color from white to black. Some oxidation haloes are obvious.

 

Thin Section (,5) Description: Brian Mason

The section shows orthopyroxene clasts, up to 4 mm across, in a matrix consisting largely of comminuted pyroxene with a small amount of plagioclase. The orthopyroxene clasts show a minor amount of augite exsolution, both blebby and lamellar. Most of the pyroxene has uniform composition, Fs29, but a few more iron-rich grains were analysed; minor constituents are CaO 0.53-2.7%, MnO 0.64-0.80%, Al2O3 0.24-0.91%, TiO2 0.16-0.31%. One grain of diopside, Wo44Fs12, was analysed. Plagioclase composition is An88-91. Accessory amounts of an SiO2 polymorph, probably tridymite, were identified. The meteorite is a diogenite.


[From AMN 11(1):]

Sample No.: LEW85313

Weight (g): 191.2

Dimensions (cm): 8x5.5x4.5

Meteorite Type: Reclassification from diogenite to howardite

 

Macroscopic Description: Roberta Score

Dull fusion crust covers most of LEW85313 except where large pieces of stone have been plucked out. This feature is abundant and makes this meteorite resemble a piece of Swiss cheese. A brownish-gray weathering rind extends from less than 1 mm to greater than 1 cm into the interior. The massive gray matrix contains both rounded and irregular inclusions that range in color from white to black. Some oxidation haloes are obvious.

 

Thin Section (,21) Description: Brian Mason

LEW85313 was originally classified as a diogenite on the basis of section 85313,5 (Antarctic Meteorite Newsletter 9 #3, p. 22), Jack Berkley suggested this sample should be reclassified and a new section was made which shows that the meteorite is a howardite, the original section was of an unusually large diogenite clast. LEW85313,21 is a microbreccia of pyroxene clasts (orthopyroxene with minor pigeonite), up to 0.9 mm across, in a comminuted groundmass of pyroxene grains, with minor plagioclase and accessory opaques (troilite and nickel-iron). Microprobe analyses show the following range in pyroxene compositions: Wo1-10Fs15-64En34-85, with a mean of Wo8Fs33 (one grain of ferroaugite, Wo37Fs38, was analysed) . Plagioclase composition range is An78-94. Two grains of a silica polymorph, probably tridymite, were analysed. This meteorite is similar to LEW85441; Antarctic Meteorite Newsletter 10, #1, p. 17), and the possibility of pairing should be considered.

Data from:
  MB76
  Table 2
  Line 2886:
Origin or pseudonym:Upper Ice Tongue
Mass (g):191.2
Class:How
Weathering grade:B
Ferrosilite (mol%):15-64
Comments:NTL=4.4±0.04; 85441 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' 16"S, 161° 21' 25"E)
Note: the NHM and MetBase coordinates are 3.1 km apart

Statistics:
     This is 1 of 40129 approved meteorites from Antarctica (plus 4494 unapproved names)
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