The new mineral hermannroseite, CaCu(PO4,AsO4)(OH), the phosphate analogue of conichalcite, from Tsumeb, Namibia
Schlueter, J; Pohl, D; Gebhard, G
The new mineral hermannroseite (IMA-CNMNC No. 2010-006) has the chemical formula CaCu(PO4,AsO4)(OH). It is the phosphate analogue of conichalcite, CaCu(AsO4)(OH) and belongs to the adelite group where it represents the first phosphate end-member of this group. Hermannroseite is orthorhombic with space group P2(1)2(1)2(1). X-ray powder diffraction studies gave a: 7.328(7), b: 9.123(7), c: 5.769(6) angstrom, V = 385.7(6) angstrom(3) , Z = 4. The strongest reflections in the X-ray powder diffraction data are as follows d(obs). (angstrom) (I, hkl): 2.808 (100, 130), 2.571 (73, 112), 3.092 (63, 201), 5.710 (56, 110) and 4.057 (37, 111). Hermannroseite was found in the Tsumeb mine, Tsumeb, Namibia. With a mean grain size of 0.7 mu m hermannroseite occurs within botryoidal agge-gates and crusts of micro crystalline conichalcite in association with hydroxylapatite, whitlockite, pseudomalachite and amorphous manganese oxides/hydroxides.
Hermannroseite is translucent with a vitreous green colour. The calculated density is 4.08 g/cm(3), the calculated mean refractive index is 1.77. Chemical analyses gave (wt.%): CaO 22.80, CuO 34.52, ZnO 0.58, P2O5 15.16, As2O5 21.88, V2O5 1.02, H2O(by difference) 4.04, sum 100.00 wt.%. The resulting empirical formula based on 5 anions is Ca-0.96(Cu1.03Zn0.02)(P(0.51)AS(0.45)V(0.03)) O-3.94(OH)(1.06).