Namuwite, (Zn,Cu)4SO4(OH)6.4H2O, a New Mineral from Wales

Richard E. Bevins, Stephen Turgoose and Peter A. Williams
Department of Geology, National Museum of Wales, Cathays Park, Cardiff, CF1 3NP
Department of Inorganic Chemistry, University College, PO Box 78, Cardiff, CF1 1XL

Abstract: Found on a specimen in the mineral collection of the National Museum of Wales, no. NMW 27.111.GR414, from the Aberllyn mine, Llanrwst mining field, North Wales, with hydrozincite on a breccia cemented by sphalerite, quartz, calcite, and ankerite. Atomic absorption and TGA analyses gave ZnO 37.8, CuO 22.0, SO3 14.9, H2O 24.5, total 99.2%, corresponding to (Zn2.50 Cu1.49)Σ3.99 S1.00 O7·7.32 H2O on the basis of total O = 7 in the anhydrous part. The ideal formula is (Zn,Cu)4SO4(OH)6·4H2O where Zn > Cu. It is hexagonal a 8.29, c 10.50 ± 0.01 Å, possible space groups P6, P¯6, P6/m, P622, P6mm, P¯6m2, P¯62m, and P6/mmm. Isomorphous with synthetic Zn,SO4(OH)66·4H2O and (Zn,Cu)4SO4(OH)6·4H2O. Strongest X-ray powder diffractions are: 10.59(100)0001, 5.31(15)0002, 4.15(25)11¯20, 2.71(42)21¯30, 2.63(41)21¯31,0004, 2.41(22)21¯32, 1.57(23)32¯52, 1.55(20)41¯51. Namuwite is pale sea-green in colour, lustre pearly, streak very pale green, H (Mohs) 2. Cleavage {0001}, perfect. Density (g/cm3) 2.77 (meas.), 2.81 (calc. on the normalized empirical formula). It is optically uniaxial, sign not determined owing to the extremely low birefringence. Refractive index n = 1.577(5)(NaD). The mineral and name have been approved by the Commission on New Minerals and Mineral Names, IMA.

Mineralogical Magazine; March 1982 v. 46; no. 338; p. 51-54; DOI: 10.1180/minmag.1982.046.338.09
© 1982, The Mineralogical Society
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