HR: 1340h
AN: P33A-1008    [Abstracts]
TI: Historical and New Perspective of Moissanite in the Canyon Diablo Meteorite
AU: * Leung, I S
EM: leung@lehman.cuny.edu
AF: Department of Geology, Lehman College of CUNY, 250 Bedford Park Blvd. West, Bronx, NY 10468 United States
AU: Winston, R
EM: RWinston@Harry Winston.com
AF: The Institute of Human Genetics and Biochemistry, 718 Fifth Avenue, New York, NY 10019 United States
AB: Silicon carbide (SiC) was reportedly found in the residue of a 50-kg sample of the Canyon Diablo meteorite dissolved in acid by Henri Moissan, and, in his honor, George F. Kunz coined the mineral name moissanite in 1904. Scholars of the same meteorite, unable to find SiC, believed that Moissan's sample might have been contaminated by synthetic SiC used in tools and abrasives. Thus, an intriguing mineralogical controversy ensued to this day. Recently, occurrence of SiC in carbonaceous chondrites has been confirmed. We present in this paper our finding of three varieties of SiC crystals in the Canyon Diablo meteorite. We found 5 crystals of SiC (size 70-150 microns) in a black nodule (1 cm in size), composed mostly of disordered graphite and diamond/lonsdaleite. The crystals are pale blue, but some have dark overgrowths of uneven thickness, and black spotty or feathery inclusions. Their forms are rounded and resorbed. Our second specimen is oxidized and friable, bearing a 2-cm nodule showing sandy and black magnetic layers. We found 3 apple-green crystals, up to 200 microns in size. Scattered over two of the sandy layers are many minute emerald-green SiC crystals. Carbon in these crystals might have a terrestrial origin. As Moissan's crystals are no longer available for re-examination, a study of large carbon nodules housed in museums might at least lend credence that meteoritic SiC crystals could be as large as ones reported by Moissan.
DE: 6215 Extraterrestrial materials
DE: 6240 Meteorites and tektites
DE: 3662 Meteorites
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting