R1: Characterization and description of minerals (Joint Session with The Gemmological Society of Japan)

[R1P-06] Cotunnite from the Nii mine, Hyogo Prefecture, Japan

*Masayuki Ohnishi¹, Shoichi Kobayashi², Daisuke Nishio-Hamane³, Norimasa Shimobayashi⁴, Takeshi Hisano¹ (1. Non, 2. Okayama Univ. of Sci., 3. ISSP, Univ. of Tokyo, 4. Sci., Kyoto Univ.)

Keywords:cotunnite, lead chloride, PbCl2, Nii mine, Hyogo

Cotunnite was found from a dump of the vein type Ag-Cu-Pb-Zn deposit of the Nii mine at Asago City, Hyogo Prefecture, Japan. The mineral occurs in cracks in quartz as white granular crystals (several micrometers in diameter), in close association with fibrous pyromorphite crystals. A SEM-EDS analysis gave the empirical formula Pb_1.00Cl_1.96 on the basis of Pb = 1 apfu. The powder X-ray diffraction data were in good agreement with a synthetic compound (ICDD-PDF 26-1150), and the refined unit-cell parameters were a = 7.623(2), b = 9.046(2) and c = 4.534(1) Å.