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New Mineral Names^*

John L. Jambor^1, and Andrew C. Roberts²

¹ Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
² Geological Survey of Canada, 601 Booth Street, Ottawa K1A 0E8, Canada

Correspondence: E-mail: JLJambor@aol.com

The first 20% of the full text of this article appears below.

BRODTKORBITE^*

W.H. Paar, D. Topa, A.C. Roberts, A.J. Criddle, G. Amann, R.J. Sureda (2002) The new mineral species brodtkorbite, Cu₂HgSe₂, and the associated selenide assemblage from Tuminico, Sierra de Cacho, La Rioja, Argentina. Can. Mineral., 40, 225–237.

Electron microprobe analyses gave Cu 26.2, Hg 40.7, Se 32.9, sum 99.8 wt%, corresponding to Cu_2.00Hg_0.98Se_2.02, ideally Cu₂HgSe₂. The mineral occurs as dark gray individual anhedral grains, up to 50 x 100 µm, and as aggregates to 150 x 250 µm. Metallic luster, brittle, dark gray streak, no cleavage or parting, uneven fracture, H = 2–3, VHN₁₀ = 91.4–131, D_calc = 7.77 g/cm³ for Z = 2 and the ideal formula. White in reflected light, weakly to moderately pleochroic from pinkish to bluish white, weak to strong bireflectance and anisotropy, rotation tints yellowish gray to mauve-gray. Reflectance percentages (WTiC standard) for R₁ and R₂ in air and in oil are, respectively, 29.60, 37.10, 15.15, 22.00 (470 nm), 27.40, 35.10, 13.30, 20.15 (546), 26.60, 34.60, 12.70, 19.80 (589), and 26.10, 34.10, 12.30, 19.25 (650). Single-crystal X-ray study indicated monoclinic symmetry, space group P2₁/n; a = 7.492(5), b = 4.177(1), c = 7.239(4) Å, ß = 114.20(5)° as refined from a powder pattern (114 Debye–Scherrer, Cu radiation), with strongest lines of 3.991(70,101), 3.576(50,110), 3.534(50,011), 3.414(50,200), 2.730(100, 12), 2.223(70,211), and 2.072(50, 13, 12).

The mineral occurs in intergrowths with berzelianite, tiemannite, umangite, and clausthalite within calcite veins at the Tuminico selenium deposit, about 30 km southwest of the village of Bajo Jagüe in the district of Sierra de Cacho, La Rioja, Argentina. The new mineral name is for Argentinian geology Prof. Milka K. de Brodtkorb (b. 1932). Type material is in the Institute of Mineralogy at the University of Salzburg, Austria, and in The Natural History . . . [Full Text of this Article]