Parádsasvárite, a new member of the malachite-rosasite group from Parádsasvár, Mátra Mountains, Hungary

Abstract

Paradsasvarite (IMA No. 2012-077) was found in the Nagy-Lapafő area, Paradsasvar, Matra Mountains, Hungary. It forms pale beige, globular aggregates up to 0.2 mm in diameter on calcite. Associated secondary minerals are smithsonite, hemimorphite, hydrozincite, aurichalcite and rosasite. The mineral was formed as an alteration product of sphalerite and chalcopyrite in a carbonate-rich environment. Paradsasvarite is translucent with a weakly vitreous, dull or silky lustre and white streak. Its Mohs hardness is about 2–3, cleavage and parting were not observed. It is brittle; the fracture is finely fibrous. Average of nine electron-microprobe analyses gave ZnO 58.08, CuO 12.60, PbO 1.27, CO2 (calc.) 19.50, H2O (calc.) 7.94, total 99.39 wt.%, corresponding to the empirical formula (Zn0.62Cu0.36Pb0.01)Σ0.99Zn1.00(CO3)(OH)2. The seven strongest lines in the X-ray powder diffraction pattern are [dhkl in A (Iobs %, hkl)] 6.054 (67, 200), 5.085 (100, 210), 3.703 (87, 310 and 220), 3.021 (25, 400 and 130), 2.971 (25, −211 and 001), 2.603 (62, −221) and 2.539 (36, 420). According to its X-ray powder diffraction data and chemical formula, paradsasvarite belongs to the malachite-rosasite group and it is isostructural with rosasite. It is monoclinic, space group P21/a, a = 12.92(1), b = 9.372(7), c = 3.159(4) A, β = 110.4(1)°, V = 358.5(5) A3, Z = 4.