SABELLIITE, A NEW COPPER-ZINC ARSENATE-ANTIMONATE MINERAL FROM SARDINIA, ITALY

Sabelliite, ideally (Cu,Zn)(2)Zn[(As,Sb)O-4] (OH)(3), is a new mineral from Is Murvonis Mine, Domusnovas, Sardinia. It occurs as intergrown aggregates or isolated crystals in a compact quartzitic matrix, in an outcrop close to worked fluorite veins of an old mine. The platy {001} disk-shaped emerald-green crystals are transparent with adamantine lu stre. Associated minerals are theisite, malachite, azurite, and tetrah edrite. Electron microprobe analyses give: Cu 34.80, Zn 15.65, Si 0.33 , As 15.04, Sb 4.96, O 28.00, H 0.67 (calculated), total 99.45 wt%. Op tically, sabelliite is nonpleochroic, uniaxial negative, with omega = 1.802(2) and epsilon =1.797(2). VHN15 microhardness = 386. Density (ca lc.)= 4.65 g/cm(3). The unit cell is trigonal with a = 8.201(1), c = 7 .315(1) Angstrom, V = 426.07(9) Angstrom(3), space group <P(3)over bar >, and Z = 3. The strongest lines in the Gandolfi X-ray pattern are (d (obs).I,hkl) 2.522(100)(121), 2.166(88)(122), 1.805(92)(123), 1.550(10 0)(410), 1.513(85)(124). The IR spectrum is also given. The mineral is named after Dr. Cesare Sabelli, researcher of the C.N.R.. Sabelliite belongs to a proposed mineral family that includes spangolite, schulen bergite, namuwite, and theisite.