ALBERT

Description: Minohlite, a new copper-zinc sulfate mineral related to schulenbergite, was found in the oxidized zone of the Hirao mine at Minoh (Minoo) City, Osaka Prefecture, Japan. The mineral occurs in cracks in altered shale as rosette aggregates up to 100 μm in diameter, composed of hexagonal platy crystals up to 50 μm in diameter and 10 μm in thickness. The associated minerals are chamosite, muscovite, smithsonite, serpierite, ramsbeckite, ‘limonite’ and chalcopyrite. Minohlite has hexagonal (or trigonal) symmetry with unit-cell parameters of a = 8.2535(11), c = 8.1352(17) Å, V = 479.93(16) Å 3 and Z = 1, and possible space groups P 6, P 6I, P 6/ m , P 622, P 6 mm , P 6I 2 m and P 6/ mmm (or P 3, P 3I, P 321, P 3 m 1, P 3I m 1, P 312, P 31 m and P 3I1 m ). The six strongest reflections in the powder X-ray diffraction pattern [ d in Å ( I ) hkl ] are 8.138 (20) 001; 4.128 (24) 110; 2.702 (100) 120; 2.564 (76) 121; 1.560 (43) 140; and 1.532 (24) 141. Electron microprobe analyses gave the following values (wt.%): CuO 37.18, ZnO 21.08, FeO 0.49, SO 3 16.78, SiO 2 0.44, and H 2 O 24.03 (by difference). The empirical formula, calculated on the basis of Cu + Zn + Fe + S + Si = 9 atoms per formula unit, is (Cu 4.43 Zn 2.45 Fe 0.06 ) 6.94 [(SO 4 ) 1.99 (SiO 4 ) 0.07 ] 2.06 (OH) 9.64 ·7.81H 2 O, which leads a simplified formula of (Cu,Zn) 7 (SO 4 ) 2 (OH) 10 ·8H 2 O where Cu 〉 Zn. The mineral is bluish-green and transparent with a pearly to vitreous lustre. The streak is pale green. Cleavage is perfect on {001}. The Mohs hardness number is less than 2. The calculated density is 3.28 g cm –3 . The mineral is named after Minoh City, where it was discovered.