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Merweville; a new South African chondritic meteorite

S. A. B. Laubscher, L. D. Ashwal, M. Tredoux, M. E. Zolensky, J. C. Loock and H. E. Praekelt
Merweville; a new South African chondritic meteorite
South African Journal of Geology (March 2001) 104 (1): 69-76

Abstract

We report petrologic, petrographic and chemical data for a newly discovered meteorite specimen from South Africa. The 7.04 kg specimen was found in ca. 1977 on the farm Waterval 64, about 30 km from the town of Merweville ( approximately 375 km northeast of Cape Town). Our research group confirmed the identity of the stone as a meteorite in 1997, and obtained a approximately 1.5 kg portion for study and classification. Externally, the specimen shows a few regmaglypts and a reddish-brown, weathered fusion crust. The sawn internal surfaces show that terrestrial weathering effects, which render a dark brownish colour to the specimen, have penetrated up to 4 to 5 cm into the meteorite. The relatively unweathered interior is light orange-brown in colour. Petrographically, the specimen shows a dominantly recrystallised texture, with a few recognisable chondrules or chondrule fragments. Shock stage is estimated at S2, and weathering grade is W2. Microprobe analyses yield: olivine (Fa (sub 23.32 + or - 0.612) , PMD = 0.52, n = 13), orthopyroxene (Fs (sub 20.59 + or - 0.54) , n = 15), kamacite (Ni = 6.48 + or - 0.24 wt.%, Co = 0.94 + or - 0.14 wt.%, n = 15), taenite (Ni = 28.9 + or - 2.3 wt.%, Co = 0.29 + or - 0.08 wt.%, n = 3), troilite (Ni = 0.10 + or - 0.11 wt.%, n = 17) and chromite (Cr/(Cr+Al) = 0.860 + or - 0.003, n = 4). No recognisable feldspar or glass is present in our thin sections of Merweville. The dominantly recrystallised but partial preservation of chondrules, apparent absence of glass, and the relative uniformity of olivine and pyroxene compositions are all consistent with classification of Merweville as petrologic type 5. Chemical and mineralogical data for the "unweathered" portion of the meteorite fall best within the L group. We conclude that Merweville is an L5 chondrite. This new specimen increases the inventory of known South African meteorites to a total of 48.


ISSN: 1012-0750
EISSN: 1996-8590
Coden: TGSAA3
Serial Title: South African Journal of Geology
Serial Volume: 104
Serial Issue: 1
Title: Merweville; a new South African chondritic meteorite
Affiliation: Rand Afrikaans University, Department of Geology, Auckland Park, South Africa
Pages: 69-76
Published: 200103
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 19
Accession Number: 2002-024680
Categories: Petrology of meteorites and tektites
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
S35°00'00" - S22°00'00", E16°00'00" - E33°00'00"
Secondary Affiliation: University of Cape Town, ZAF, South AfricaNASA, Johnson Space Center, USA, United StatesUniversity of the Free State, ZAF, South Africa
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200210
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