14
November 2002
Extraterrestrial graphite: Carbon copies iron
The giant Canyon Diablo meteorite, cause of a 1.3-km-wide crater in the Arizona desert, has brought some remarkable graphite chemistry to Earth. The meteorite, made up largely of iron and nickel, contains large graphite inclusions packed with metal. These inclusions are strongly ferromagnetic, but only about two-thirds of the magnetization can be accounted for by magnetic minerals — the rest is somehow associated with carbon. This appears to confirm recent reports of very weak high-temperature ferromagnetism in graphite, and may reflect a proximity effect at the interface with magnetic kamacite or magnetite inclusions.
Ferromagnetism of a graphite nodule from the Canyon
Diablo meteorite
J. M. D. COEY, M. VENKATESAN,
C. B. FITZGERALD, A. P. DOUVALIS & I. S. SANDERS
Nature 420,
156–159 (2002); doi:10.1038/nature01100
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