Leisingite, Cu(Mg,Cu,Fe,Zn)2Te6+O6·6H2O, a New Mineral Species from the Centennial Eureka Mine, Juab County, Utah

Andrew C. Roberts, Lee A. Groat, Joel D. Grice, Robert A. Gault, Martin C. Jensen1, Elizabeth A. Moffatt and John A. R. Stirling
Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
Department of Geological Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia, Canada V6T 1Z4
Research Division, Canadian Museum of Nature, Ottawa, Ontario, Canada K1P 6P4
Mackay School of Mines, University of Nevada, Reno, Nevada, USA 89557-0047
Canadian Conservation Institute, 1030 Innes Road, Ottawa, Ontario, Canada K1A 0M5
Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, Canada K1A 0E8
1Present address: 121-2855 Idlewid Drive, Reno, Nevada, USA 89509

Abstract: Leisingite, ideally Cu(Mg,Cu,Fe,Zn)2Te6+O6·6H2O, is hexagonal, P3 (143), with unit-cell parameters refined from powder data: a = 5.305(1), c = 9.693(6) Å, V = 236.2(2) Å3, c/a = 1.8271, Z = 1. The strongest six reflections of the X-ray powder-diffraction pattern [d in Å (I) (hkl)] are: 9.70 (100) (001), 4.834 (80) (002), 4.604 (60) (100), 2.655 (60) (110), 2.556 (70) (111) and 2.326 (70) (112). The mineral is found on the dumps of the Centennial Eureka mine, Juab County, Utah, U.S.A. where it occurs as isolated, or rarely as clusters of, hexagonal-shaped very thin plates or foliated masses in small vugs of crumbly to drusy white to colourless quartz. Associated minerals are jensenite, cesbronite and hematite. Individual crystals are subhedral to euhedral and average less than 0.1 mm in size. Cleavage {001} perfect. Forms are: {001} major; {100}, {110} minute. The mineral is transparent to somewhat translucent, pale yellow to pale orange-yellow, with a pale yellow streak and an uneven fracture. Leisingite is vitreous with a somewhat satiny to frosted appearance, brittle to somewhat flexible and nonfluorescent; H(Mohs) 3–4; D(calc.) 3.41 for the idealized formula; uniaxial negative, ω = 1.803(3), ɛ = 1.581 (calc.). Averaged electron-microprobe analyses yielded CuO 24.71, FeO 6.86, MgO 6.19, ZnO 0.45, TeO3 36.94, H2O (calc.) [21.55], total [96.70] wt.%, leading to the empirical formula Cu1.00(Mg0.77Cu0.56Fe0.48Zn0.03)Σ1.84Te1.066+O6.02·5.98H2O based on O = 12. The infrared absorption spectrum shows definite bands for structural H2O with an O-H stretching frequency centered at 3253 cm−1 and a H-O-H flexing frequency centered at 1670 cm−l. The mineral name honours Joseph F. Leising, Reno, Nevada, who helped collect the discovery specimens.

Keywords: leisingite • new mineral • Centennial Eureka mine • Juab County • Utah • U.S.A. • X-ray data • electron-microprobe analyses • optical data • infrared-absorption study

Mineralogical Magazine; August 1996 v. 60; no. 401; p. 653-657; DOI: 10.1180/minmag.1996.060.401.11
© 1966, The Mineralogical Society
Mineralogical Society (www.minersoc.org)