Graphite in Natural and Experimental Carbonate Systems

D. C. Gellatly
Research Institute of African Geology, Department of Geology, University of Leeds1
1Present address: Bureau of Mineral Resources, P.O. Box 378, Canberra, Australia.

Summary: Graphite occurs in the Darkainle nepheline syenite complex, Somali Republic, as small drop-like grains in an altered ankeritic carbonatite; it has been recorded previously from carbonate-bearing nepheline syenites and kimberlites. Experimental evidence indicates that siderite decomposes to a stable association of magnetite and graphite within the PT ranges 500 to 10 000 bars and 455 to 745° C. The graphite in carbonatite and other alkaline igneous rocks may have been formed similarly by the decomposition of siderite or iron-rich carbonates.

Mineralogical Magazine; September 1966 v. 35; no. 275; p. 963-970; DOI: 10.1180/minmag.1966.035.275.08
© 1966, The Mineralogical Society
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