Tsugaruite, Pb_4As_2S_7, from the Yunosawa mine, Aomori prefecture, Japan

摘要

Tsugaruite, Pb_4As_2S_7, a new Pb-As sulphosalt from Japan, is orghorhombic, Pnn2 or Pnnm, a 15.179(1), b 38.195(1), c 8.0745(5)A; c'=1/2c; Z=16[Pb_4As_2S_7]. Microprobe analyses gave Pb 68.70, Tl 0.13, As 12.45, S 18.64, total 99.92 wt.