Abstract

The mineralogy, texture, and chemical composition of metallic spheroids from Meteor Crater, Arizona, were studied in detail. The spheroidal to elongate particles studied average 0.5 mm across and characteristically are coated by siliceous glass containing numerous minute fragments of quartz. Some spheroids consist of a fine-grained granular kamacite core, commonly intergrown and surrounded by a go thite-like iron oxide and maghemite. Associated with the kamacite is an interstitial pink mineral optically similar to the pink schreibersite inclusions in the metallic spherules in philippinites and indochinites. X-ray powder patterns of this pink mineral from the Meteor Crater spheroids are also identical to that of schreibersite.

Electron microprobe analysis shows:

Ni%Fe%Kamacite2247497Maghemite565962Goethitelikemineral2144560

The wide range of nickel content in kamacite, the fine-grained texture, and the siliceous glass coating on the spheroids indicate that the Meteor Crater spheroids probably condensed from a vapor or melt produced during impact of the meteorite. The range in nickel content in the kamacite of the Philippine and Indochina tektite spherules is nearly identical to that of the kamacite in the spheroids from Meteor Crater, whose meteoritic origin is certain.

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