BAUMSTARKITE FROM THE KORYU MINE, HOKKAIDO, JAPAN

Baumstarkite ideally AgSbS2, was found as aggregates of euhedral crystals in the Koryu mine, Hokkaido, Japan. The optical properties, chemical composition, and cell parameters of this mineral are presented. The compositional ranges are from 1.8 to 7.0 at.% As (7.4 to 28.2 mol.% AgAsS2). The unit cell of a sample with 10 mol.% AgAsS2 is triclinic, P (1) over bar with a 7.778(1), b 8.326(1), c 8.814(1) angstrom, alpha 100.90(1), beta 104.01(1), gamma 90.06(1)degrees, and V 543.2(1) angstrom(3); these values are in very good accordance with those of the type mineral as well as those of synthetic material.