• journal_title：Mineralogical Magazine
• Contributor：L. Bindi ; C. Carbone ; D. Belmonte ; R. Cabella ; R. Bracco
• Publisher：Mineralogical Society of Great Britain and Ireland
• Date：2013-06-01
• Format：text/html
• Language：en
• Identifier：10.1180/minmag.2013.077.4.07
• journal_abbrev：Mineralogical Magazine
• issn：0026-461X
• volume：77
• issue：4
• firstpage：475
• section：Articles

d="p-1">Weissite, Cu_2–xTe (x ≈ 0.21), a very rare copper telluride, occurs in a sample from the Gambatesa mine, Val Graveglia, Liguria, Italy, where it occurs as purplish black anhedral grains up to 0.1 mm in length and shows a black streak. No cleavage is observed and the Vickers hardness (VHN₁₀₀) is 142 kg/mm². Weissite is dark bluish black, weakly pleochroic, and moderately anisotropic in bluish tints. Reflectance percentages in air for R_min and R_max are 37.0, 38.4 (471.1 nm), 33.2, 34.2 (548.3 nm), 31.2, 32.1 (586.6 nm), and 28.6, 31.0 (652.3 nm), respectively.

d="p-2">Weissite is trigonal and belongs to the space group P3m1 with the following unit-cell parameters: a = 8.3124(7) Å, c = 21.546(1) Å, V = 1289.3(2) ų, and Z = 24. Electron microprobe analyses gave the chemical formula (Cu_1.62Ag_0.04Au_0.04Fe_0.04Sb_0.04)_Σ=1.78(Te_0.96S_0.02Se_0.02). The crystal structure has been solved and refined to R = 1.95%. It consists of Cu and Te polyhedra forming complex crystal-chemical environments as is typical of many intermetallic compounds. The exceedingly short bond distances observed among the metals are discussed in relation to other copper tellurides and pure metals.