The Bencubbin Meteorite: Further Details, Including Microscopic Character of Host Material and Two Chondrite Enclaves

G. J. H. McCall1
1Reader in Geology, University of Western Australia; Honorary Associate, Western Australian Museum.

Summary: The Bencubbin meteorite and some of its enclaves have been studied in thin section under transmitted light: supporting X-ray diffraction and chemical data have been supplied by the Smithsonian Institution, Washington. These results show the host material to consist of clinoenstatite and a little olivine (both nearly pure magnesian varieties) set in an opaque (cryptocrystalline ?) base, which is, in turn, enclosed in a mesh-work of nickel-iron, of composition equivalent to a hexa-hedrite. Two enclaves are revealed as: an atypical olivine-hypersthene chondrite (in the mode, the olivine is Fa19, and pigeonite takes the place of orthopyroxene, but the chemical analysis is typical except for a small but appreciable carbon content); and an enstatite chondrite displaying crudely formed chondrules (chemically typical, with a small but appreciable carbon content).

The chondrite enclaves are not recrystallized: though Lovering has referred to the first as ‘thermally metamorphosed’, and both are dark coloured, there seems to be little evidence of the effect of the metallic host, which must surely have been molten, on the chondrite enclaves, which seem to have been able to survive in this environment without mineralogical or textural modification.

Lovering has stressed the importance of this meteorite in its bearing on meteorite provenance and genesis, and the further implications of this present study are discussed briefly.

Mineralogical Magazine; March 1968 v. 36; no. 281; p. 726-739; DOI: 10.1180/minmag.1968.036.281.14
© 1968, The Mineralogical Society
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