The new mineral hermannroseite, CaCu(PO4,AsO4)(OH), the phosphate analogue of conichalcite, from Tsumeb, Namibia
Schlüter, Jochen; Pohl, Dieter; Gebhard, Georg
published: Apr 1, 2011
ArtNo. ESP154018802004, Price: 29.00 €
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 P212121. X-ray powder diffraction studies gave a: 7.328(7), b: 9.123(7), c: 5.769(6) Å, V = 385.7(6) Å3, Z = 4. The strongest reflections in the X-ray powder diffraction data are as follows dobs. (Å) (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 μm hermannroseite occurs within botryoidal aggegates 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/cm3, 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 Ca0.96(Cu1.03Zn0.02)(P0.51As0.45V0.03) O3.94(OH)1.06.