A Rare Au-Sb Telluride Pampaloite from the Svetlinsk Gold-Telluride Deposit, South Urals, Russia

Abstract

Pampaloite AuSbTe, a rare gold-antimony telluride that was first described in 2019 from the Pampalo gold mine, Finland, was found in samples from the large Svetlinsk gold-telluride deposit, South Urals, Russia. Optical microscopy, scanning electron microscopy, electron microprobe analysis, reflectance measurements, electron backscatter diffraction and Raman spectroscopy were used to study eight grains of pampaloite. Pampaloite forms inclusions (5–30 μm) in quartz together with other tellurides (typically petzite), native gold and, less often, sulfides. In reflected light, pampaloite is white or creamy white in color with weak anisotropism and without internal reflections. The empirical formula calculated on the basis of 3 apfu is Au0.97–1.07Ag0–0.02Sb0.96–1.04Te0.96–1.04 (n = 18). The holotype pampaloite structure was used as a reference and provided the perfect match for an experimental EBSD pattern (12 bands out of 12, mean angle deviation 0.19°). Raman spectra are reported for the first time for this mineral. All studied pampaloite grains exhibit vibrational modes in the range 60–180 cm−1. Average peak positions are 71, 108, 125, 147 and 159 cm−1. According to experimental data for the Au-Sb-Te system, we estimate the upper temperature range of pampaloite crystallization at the Svetlinsk deposit to be 350–430 °C.

Montbrayite from the Svetlinsk Gold–Telluride Deposit (South Urals, Russia): Composition Variability and Decomposition

“…Gold mineralization is represented by disseminated sulfides in the host rocks (C Au up to 1 g/t) and by sulfide-quartz veins (C Au = 0.8-2.5 g/t). Three mineralization stages have been recognized [23,24]: (1) the disseminated quartz-pyrite-pyrrhotite stage, with rare chalcopyrite, tetrahedrite, galena, and native gold; (2) the quartz-pyrite vein stage, with scheelite; (3) the gold-telluride stage (the main productive one). Native gold (620-965‰) is often associated with tellurides that are common and varied in the ore veins.…”

“…Cont. Mode at 103 cm −1 of Bi 2 Te 3[44] Mode at 105 cm −1 of Cu-doped Sb 2 Te 3[48] Mode at 102 cm −1 of AuAgTe 4[42] Mode at 98 cm −1 of Se-rich AuTe 2[49] Mode at 98 cm −1 of Bi 2 Te 3 Te vibration (116 cm −1 ) of Sb 2 Te 3[43] Modes at 117 and 121 cm −1 of AuSb 2[51] Mode at 120 cm −1 of Bi 2 Te 3 and mode at 112 cm −1 of Sb 2 Te 3[44] Mode at 120 cm −1 of Cu-doped Sb 2 Te 3[48] Mode at 117 cm −1[46] Mode at 112 cm −1 of Sb 2 Te 3[52] Mode at 119 cm −1[53] Mode at 120 cm −1[47] Mode at 116 cm −1 of Bi 2 Te 3[50] Modes 114 and 121 cm −1 of AuAgTe 4[42] 135Te-Te vibration (137 cm −1 ) of Sb 2 Te 3[43] Mode at 134 cm −1 of Bi 2 Te 3[44] Mode at 135 cm −1 of Cu-doped Sb 2 Te 3 Te vibration (162 cm −1 ) of Sb 2 Te 3[43] Modes at 155 and 162 cm −1 of AuSb 2[51] Mode at 158 cm −1 of AuAgTe 4[42] Mode at 160 cm −1 of Cu-doped Sb 2 Te 3[48] Mode at 159 cm −1 of AuSbTe[45] 177 171Mode at 172 cm −1 of AuTe 2[29] Mode at 176 cm −1 of Au 2.73 Te 6.23 Se 3.84[49] Mode at 174 to 178 cm −1 of synthetic Au 3 X 10 (X = Te, Se, S)…”