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| Morokweng | |||||||||||||||||||||||||||||||
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| Basic information | Name: Morokweng This is an OFFICIAL meteorite name. Abbreviation: There is no official abbreviation for this meteorite. Observed fall: No Year found: 2004 Country: South Africa Mass:  750 g | ||||||||||||||||||||||||||||||
| Classification history: |
This is 1 of 2890 approved meteorites (plus 2 unapproved names) classified as LL6. [show all] Search for other: LL chondrites, LL chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7) | ||||||||||||||||||||||||||||||
| Comments: | Approved 12 Feb 2009 | ||||||||||||||||||||||||||||||
| Writeup |
Writeup from MB 95:
Morokweng 26°22′20.89′′S, 23°31′26.24′′E Northwest Province, South Africa, near the small town of Morokweng Find June 2004 LL6 ordinary chondrite History: The meteorite was found by Dr. Marco Andreoli in June 2004 while conducting a detailed petrographic description of the M3 borehole. The M3 borehole had been drilled in 2000 to investigate the mineral potential of the ~30 km meltsheet of the ~144 Ma Morokweng impact crater. The meteorite was intersected at a depth of ~766 m within the 870 m thick meltsheet. Petrographic and compositional evidence indicates the presence of many other, smaller fragments in various stages of recrystallization (Hart et al. 2002). Physical characteristics: The main mass is ~750 g. The meteorite is mostly unaltered, apart from a thin (~1 mm) brown corona containing unidentified Fe silicates and K-rich sheet silicates interpreted to be the result of alteration by the meltsheet. Petrography W. D. Maier (UQué, Pretoria), M. A. G. Andreoli (SANEC, Wits), I. McDonald (Cardiff), M. D. Higgins (UQué), A. J. Boyce (SUERC), A. Shukolyukov (Scripps), G. W. Lugmair (Scripps), L. D. Ashwal (Wits), P. Graeser (UPret), E. Ripley (IU), and R. Hart (Ithemba): Apart from the thin (1 mm) corona containing brown alteration minerals, the meteorite is seemingly unaltered. Petrographic study revealed diagnostic features of a highly equilibrated chondrite breccia, including numerous subangular chondrite fragments, and several well-preserved chondrules of porphyritic pyroxene, barred olivine, and radial pyroxene. The number of preserved chondrules is relatively low. Both minerals commonly show undulatory and mosaic extinction. The matrix material has a well-developed granular texture with 120° triple junctions. Geochemistry: Both olivine (Fo67–70) and orthopyroxene (En69–73) are homogenous within individual grains and throughout the meteorite. Plagioclase is mostly An33–50, some to An17, chromite has 44–48% Cr2O3. Pyrrhotite has composition Fe0.85–0.87S and pentlandite (Fe,Ni)1.02–1.10S. The bulk chemistry of the large clast is chondritic, although U, Th, La and Ce are enriched and Na, K are depleted compared to the average compositions for ordinary chondrites. Absolute PGE (Ir = 234 ppb; Ru = 351 ppb; Rh = 81 ppb; Pt = 478 ppb; Pd = 361 ppb), Ni (5850 ppm) and Co (326 ppm) concentrations are ~30–40% lower than in average LL chondrites. Despite the absence of metal, the bulk Fe content of the clast is chondritic. Bulk S isotope analyses yielded δ34S values of −0.1‰ and −0.4‰, and individual sulphide minerals analysed by in situ laser combustion revealed a range of values from −0.9‰ to +0.1‰. 53Cr/52Cr ratio in the large clast is 0.38 ± 0.05ε. Classification: LL6 chondrite, shock stage S5, weathering grade W0. Specimens: A total of ~20 g is on deposit at the Transvaal Museum, Pretoria, South Africa. Dr W. D. Maier holds the main mass. Dr. M. Andreoli holds 4 small pieces (between 2 and 22 g). | ||||||||||||||||||||||||||||||
| Data from: MB95 Table 1 Line 2: |
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| Institutions and collections |
TM: Geoscience Museum, Transvaal Museum, P. O. Box 413, Pretoria 0001, South Africa (institutional address; updated 3 Mar 2011) Wits: Curator of Fossil and Rock Collections c/o Evolutionary Studies Institute University of the Witwatersrand Private Bag 3 WITS 2050 Johannesburg South Africa, South Africa (institutional address; updated 3 May 2019) Cardiff: School of Earth, Ocean & Planetary Sciences, Cardiff University, Cardiff CF10 3YE, United Kingdom (institutional address; updated 17 Apr 2009) Ithemba: Ithemba LABS - Gauteng, Wits 2050, South Africa (institutional address; updated 17 Apr 2009) IU: Department of Geological Sciences, Indiana University, Bloomington, Indiana 47405-7000, United States (institutional address; updated 17 Apr 2009) SANEC: South African Nuclear Energy Corporation, Pretoria 0001, South Africa (institutional address; updated 17 Apr 2009) Scripps: Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, United States (institutional address; updated 17 Apr 2009) SUERC: Scottish Universities Environmental Research Centre, East Kilbride G75 0QF, United Kingdom (institutional address; updated 17 Apr 2009) UPret: Department of Geology, University of Pretoria, Pretoria 0002, South Africa (institutional address; updated 17 Apr 2009) UQué: Sciences de la Terre, Université du Québec à Chicoutimi, Chicoutimi, Quebec G7H 2B1, Canada (institutional address; updated 17 Apr 2009) |
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| Catalogs: |
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| References: | Published in Meteoritical Bulletin, no. 95, MAPS 44, 429-462 (2009)
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Geography:
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Statistics: This is 1 of 3 approved meteorites from North West, South Africa (plus 1 unapproved name) (plus 2 impact craters) This is 1 of 49 approved meteorites from South Africa (plus 2 unapproved names) (plus 4 impact craters) | ||||||||||||||||||||||||||||||
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