抄録
Munakataite, Pb2Cu2(Se4+O3)(SO4)(OH)4, occurs as a thin coating on a fracture in a quartz vein containing Cu-Zn-Pb-Ag-Au ore minerals in the Kato mine, Munakata City, Fukuoka Prefecture, Japan. It is monoclinic with the space group P21/m and lattice parameters a = 9.766(8), b = 5.666(5), c = 9.291(10) Å, β = 102.40(8)°, V = 502.1(8) Å3, and Z = 2. An electron microprobe analysis gave the empirical formula as Pb2.03(Cu1.94Ca0.01)Σ1.95(Se4+O3)1.00(SO4)1.02(OH)3.92 on the basis of Pb + Cu + Ca + Se + S = 6 apfu and the calculated (OH) with a charge balance. Munakataite is a member of the linarite-chenite group, and it is the first selenite mineral in Japan, corresponding to a (SO4)-dominant analogue of schmiederite. The mineral occurs as light-bluish aggregates composed of minute fibrous crystals up to 30 μm long. The calculated density is 5.526 g/cm3, and Mohs hardness is less than 2.
