Pauladamsite, Cu (sub 4) (SeO (sub 3) )(SO (sub 4) )(OH) (sub 4) .2H (sub 2) O, a new mineral from the Santa Rosa Mine, Darwin District, California, USA

Pauladamsite (IMA2015-005), Cu (sub 4) (SeO (sub 3) )(SO (sub 4) )(OH) (sub 4) .2H (sub 2) O, is a new mineral from the Santa Rosa mine, Darwin district, Inyo County, California, USA, where it occurs as a secondary oxidation-zone mineral in association with brochantite, chalcanthite, gypsum, ktenasite, mimetite, schulenbergite and smithsonite on limonitic gossan. Pauladamsite forms green, multiply twinned blades up to 0.5 mm long grouped in radial sprays. The streak is pale green. Crystals are transparent and have vitreous to silky lustre. The Mohs hardness is approximately 2, the tenacity is brittle, the fracture is irregular and crystals exhibit one perfect cleavage on [001]. The calculated density is 3.535 cm (super 3) Electron microprobe analyses provided: CuO 48.96, ZnO 3.56, SeO (sub 2) 18.82, SO (sub 3) 13.90, H (sub 2) O 13.29 (calc.), total 98.53 wt.%. The empirical formula (based on 13 O apfu) is: (Cu (sub 3.55) Zn (sub 0.25) ) (sub Sigma 3.80) Se (sub 0.98) SO (sub 13) H (sub 8.50) Pauladamsite is triclinic, P (sub 1) , a = 6.0742(7), b = 8.4147(11), c = 10.7798(15) A, alpha = 103.665(7), beta = 95.224(7), gamma = 90.004(6) degrees , V = 533.03(12) A (super 3) and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [d (sub obs) in A(I)(hkl)]: 10.5(46)(011); 3.245(100)(001); 5.81(50)(011); 2.743(49)(112); 3.994(67)(012); 3.431(23)( (sub 1) 12, (sub 12) 1, (sub 1) 20); and 2.692(57)(0 (sub 3) 2, (sub 1) 22, (sub 21) 2); and 2.485(39)(2 (sub 1) 2, (sub 13) 2, 0 (sub 2) 4). The structure of pauladamsite (R (sub 1) = 10.6% for 2086 F (sub o) > 4sigma F) contains Cu (super 2+) O (sub 6) octahedra, SO (sub 4) tetrahedra and Se (super 4+) O (sub 3) pyramids. There are four different CuO (sub 6) octahedra, each of which exhibits typical Jahn-Teller distortion, with four short equatorial Cu-O bonds and two much longer apical Cu-O bonds. The CuO (sub 6) octahedra share edges to form five-octahedra-wide bands extending along [100]. Adjacent bands are connected in the [01 (sub 1) ] direction by bridging SO (sub 4) tetrahedra and in the [011] direction by bridging Se (super 4+) O (sub 3) pyramids, thereby forming a framework.