Die Kristallstruktur von Galchait [Hg0,76(Cu,Zn)0,24]12Tl0,96(AsS3)8*

Abstract

Abstract Galkhaite (from the Getchell Mine, Humboldt County, Nevada) was investigated roentgenographically. The mineral crystallizes in the cubic space group I[unk]3m with a = 10.379 ± 0.004 Å and one formula unit [Hg0.76(Cu,Zn)0.24]12-Tl0.96(AsS3)8 in the unit cell; d x = 5.31 g/cm3. The structure was solved by Patterson syntheses and refined by full-matrix least-squares method to an R value of 4.5% for all 132 independent reflections. The Hg atom is surrounded by 4 S at a distance of 2.503 Å at the corners of a regular tetrahedron. Tl is distributed statistically in the 2a position and has a regular coordination of 12 S (Tl–S = 3.863 Å). The As atoms show a trigonal-pyramidal coordination of 3 S at a distance of 2.265 Å. The (S–As–S) angle is 93.9°. The pyramides are isolated one from the other, corresponding to type II. a 1 (φ = 3) of the classification of Nowacki (1968/69).