The Petrology of the Mount Padbury Mesosiderite and Its Achondrite Enclaves

G. J. H. McCall1, H. B. Wiik and A. A. Moss
Arizona State University, Tempe, Arizona, Department of Chemistry.
British Museum (Natural History), Department of Mineralogy.
1University of Western Australia, Geology Department. Honorary Associate, Western Australian Museum.

Summary: The petrography of the Mount Padbury meteorite, previously briefly recorded, is described in some detail. Both the metalliferous host material of the mesosiderite and the varied range of silicate-rich, virtually metal-free enclaves (including both familiar achondrite material and unfamiliar achondrite material) are described. Eucrite, brecciated eucrite, and a peculiar ‘shocked’ form of eucrite (resembling some terrestrial flaser-gabbros) are the calcium-rich achondrite types represented; hypersthene achondrite (including typical diogenite material and unfamiliar material) and olivine achondrite (granular aggregates of olivine not entirely similar to the unique chassignite and single crystals up to 4 in. in length) are the calcium-poor achondrite types represented. The eucrite displays more or less uniform mineralogy, but the mineral constituents are present in varying proportions, and there is a wide range of textural variations recognized. The silicate grain fragments enclosed in the metallic reticulation to form the mesosiderite host material are, significantly, entirely of minerals seen within the achondrite enclaves—plagioclase, hypersthene, pigeonite, olivine, and tridymite.

These results include microscopic analysis of thin sections and polished sections, X-ray diffraction studies, optical determination of refractive indices using mineral grain mounts, and chemical analyses.

The wider implications of this new and unique meteorite find are briefly considered.

Mineralogical Magazine; December 1966 v. 36; no. 276; p. 1029-1060; DOI: 10.1180/minmag.1966.036.276.01
© 1966, The Mineralogical Society
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