Jensenite, Cu3Te6+O6 center dot 2H(2)O, a new mineral species from the Centennial Eureka mine, Tintic district, Juab county, Utah

Jensenite, ideally Cu3Te6+O6 . 2H(2)O, is monoclinic, P2(1)/n (14), with unit-cell parameters refined from powder data: a 9.204(2), b 9.170(2), c 7.584(1) Angstrom, beta 102.32(3)degrees, V 625.3(3) Angstrom(3), a:b:c 1.0037:1:0.8270, Z = 4. The strongest six reflections of the X-ray powder-diffraction pattern [d in Angstrom(I)(hkl)] are: 6.428(100)((1) over bar 01,110), 3.217(70)((2) over bar 02), 2.601(40)(202), 2.530(50)(230), 2.144(35)((3) over bar 31) and 1.750(35)((4) over bar 32). The mineral is found on the dumps of the Centennial Eureka mine, Juab County, Utah, where it occurs as isolated crystals or as groups of crystals on drusy white quartz. Associated minerals are mcalpineite, xocomecatlite and unnamed Cu(Mg,Cu,Fe,Zn)(2)Te6+O6 . 6H(2)O. Individual crystals of jensenite are subhedral to euhedral, and form simple rhombs that are nearly equant. Some crystals are slightly elongate [101], with a length-to-width ratio up to 2:1. The largest crystal is approximately 0.4 mm in size; the average size is between 0.1 and 0.2 mm. Cleavage {(1) over bar 01} fair. Forms are: {(1) over bar 01} major; {110} medium; {100} minor; (301), {201}, {203}, {(1) over bar 02}, {010} very small. The mineral is transparent, emerald green, with a less intense streak of the same color and an uneven fracture. Jensenite is adamantine, brittle and nonfluorescent; H (Mohs) 3-4; D (calc.) 4.78 for the idealized formula, 4.76 g/cm(3) for the empirical formula. In a polished section, jensenite is very weakly bireflectant and nonpleochroic. In reflected plane-polarized light in air, it is a nondescript grey, and in oil, it is a much darker grey in color with a brownish tint, with ubiquitous bright green internal reflections. Anisotropy is not detectable. Measured values of reflectance, in air and in oil, are tabulated. Electron-microprobe analyses yielded CuO 50.91, ZnO 0.31, TeO3 38.91, H2O (calc.) [8.00], total [98.13] wt.%. The empirical formula, derived from crystal-structure analysis and electron-microprobe analyses, is (Cu2.92Zn0.02Sigma 2.94Te1.016+O5.97. 2.03H(2)O), based on O = 8. The mineral name honors Martin C. Jensen, Reno, Nevada, who discovered the mineral.