Die Kristallstruktur von Baumhauerit*

Abstract

The crystal structure of baumhauerite Pb 11,6 As 15,7 Ag 0,6 S 36 is redetermined. The unit cell is triclinic with a = 22.80 ± 0.01 Å, b = 8.357 ± 0.005 Å, c = 7.894 ± 0.005 Å, α = 90°3′ ± 2′, β = 97°16′ ± 4′, γ = 89°55′ ± 2′. The space group is P 1. Among twelve independent Pb atoms, the eight “paired” (1, 2, 6, 7, 8, 9, 11, 12) are surronded by nine S atoms, the four “unpaired” (3, 4, 5, 10) are surrounded by seven S atoms. The As atoms are coordinated by S atoms in a trigonal pyramidal configuration. The Pb(4) is partially replaced by As. The As(5) occupies statistically two neighbouring places 5 a , 5 b . The As(4) is partially replaced by Ag. AsS 3 pyramids form chains of finite length.