Stöfflerite, (Ca,Na)(Si,Al)O8 in the Hollandite Structure: A New High-Pressure Polymorph of Anorthite from Martian Meteorite NWA 856
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We present the crystal structure, composition, and occurrence of stöfflerite, the naturally occurring Ca-aluminosilicate with hollandite-type structure. Stöfflerite is a high-pressure polymorph of anorthite and an approved mineral. The type material was found in the shergottitic martian meteorite Northwest Africa 856. Type stöflerite (Sto60Lin40) assumes space group I4/m with unit-cell dimensions a = 9.255(1) Å, c = 2.742(3) Å, V = 235.1(2) Å3, and Z = 2.
High pressure; hollandite; new mineral; shock compression
Stöfflerite, (Ca,Na)(Si,Al)O8 in the Hollandite Structure: A New High-Pressure Polymorph of Anorthite from Martian Meteorite NWA 856.
American Mineralogist, 106(4),