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Grosvenor Mountains 95633
Basic information Name: Grosvenor Mountains 95633
     This is an OFFICIAL meteorite name.
Abbreviation: GRO 95633
Observed fall: No
Year found: 1995
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 58.1 g
Antarctic Meteorite Newsletter:  AMN 20(2)  (1997)  Eucrite-br
Meteoritical Bulletin:  MB 82  (1998)  Eucrite-br
NHM Catalogue:  5th Edition  (2000)  Eucrite-br
MetBase:  v. 7.1  (2006)  Eucrite-pmict
Antarctic Meteorite Newsletter:  AMN 33(1)  (2010)  Howardite
Recommended:  Howardite    [explanation]

This is 1 of 439 approved meteorites classified as Howardite.   [show all]
Search for other: Achondrites, HED achondrites, and Howardites
Comments: Revised 12 Feb 2010: reclassified in AMN 33(1)
Writeup from AMN 20(2):
Sample No.:GRO95633
Location:Grosvenor Mountains
Dimensions (cm):4.7x2.5x3.0
Weight (g):58.10
Meteorite Type:Eucrite (brecciated)

Macroscopic Description: Cecilia E. Satterwhite
95% of the exterior of this achondrite is covered by shiny, black fusion crust. The fusion crust appears glassy in some areas. The interior reveals a complex breccia consisting of a wide variety of clasts in a light gray matrix. The largest clasts are fine grained dark gray melts. There is one large white (plagioclase) clast and several coarse grained yellow-green mineral clasts. Some areas are mottled with black and white patches. Some oxidation is scattered in the interior but is heavier along the edges.

Thin Section (,3) Description: Brian Mason
The section shows a microbreccia of plagioclase clasts (up to 1.8 mm) and basaltic fragments in a groundmass of comminuted plagioclase and dark brown glass. A few metal grains are present, surrounded by brown limonitic staining. Plagioclase composition is fairly uniform, An91-92; pyroxene composition in a basaltic clast ranges from Wo5Fs32 to Wo2Fs57. The meteorite is a brecciated eucrite.

GRO95633 TS - Plane Polarized LightGRO95633 TS - Cross Polarized Light
Plane-Polarized LightCross-Polarized Light

Writeup from AMN 33(1):
GRO 95633 original classification in AMN 20, no. 2, as a brecciated eucrite. Subsequent studies and numerous thin sections reveal various eucritic lithologies and also orthopyroxene. Bulk compositions of [1, 2] indicate clear >10% mixture of diogenitic material with the eucritic material. Therefore this sample is reclassified as a howardite.

[1] Mittlefehldt, D.W., and Lindstrom, M.M. (2003) Geochemistry of eucrites: Genesis of basaltic eucrites, and Hf and Ta as petrogenetic indicators for altered Antarctic eucrites. Geochimica et Cosmochimica Acta, 67, no. 10, 1911-1935.
[2] C.Okamato et al., Papers 28th Symp. Ant. Met., NIPR Tokyo, (2004) p.68 (abs.).
Data from:
  Table A1
  Line 265:
Origin or pseudonym:Outer Cecily
Mass (g):58.1
Class:Eu "br"
Weathering grade:B
Ferrosilite (mol%):32-57
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References: Published in Antarctic Meteorite Newsletter 20(2) (1997), JSC, Houston
Published in Antarctic Meteorite Newsletter 33(1) (2010), JSC, Houston
Published in Meteoritical Bulletin, no. 82, MAPS 33, A221-A240 (1998)
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Photographs from AMN:
Photograph from unknown source A photo is in the write-up above
Photos from the Encyclopedia of Meteorites:
courtesy Dr Carlton Allen, JSC-KT, NASA         

     Catalogue of Meteorites:   (85° 40'S, 175° 0'E)
     Recommended::   (85° 40'S, 175° 0'E)

     This is 1 of 43856 approved meteorites from Antarctica (plus 3802 unapproved names)
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