Thallium-rich mineralization at Jas Roux, Hautes-Alpes, France: A complex epithermal, sediment-hosted, ore-forming system
The Jas Roux deposit, which is hosted by strongly silicified Triassic sedimentary rocks, is characterized by a complex mineralization of pyrite, sphalerite, twinnite, zinckenite, andorite, stibnite, chabourneite, parapierrotite, pierrotite, smithite, laffittite, routhierite, aktashite, wakabayashilite, realgar and barite, plus four new mineral phases: (i) a phase Pb9Ag(Sb,As)13S29 with optical properties similar to jamesonite, VHN25 = 165 kg/mm2, a composition close to the ideal formula, and a monoclinic unit-cell with a = 17.640, b = 18.464, c = 3.967 Å, ß = 90°48', V = 1292 Å 3, Z = 1, Dcalc = 5.51; (ii) a phase Tl(As, Sb)10S16 that is X-ray amorphous; (iii) a phase Tl(Sb,As)7S11 that is weakly anisotropic with reflectivity close to chabourneite; and (iv) a phase Ag2SbAsS4, representing a reaction product between smithite and chabourneite. Hypotheses on the genesis of the deposit, based on the determined crystallization sequence, reveal similarities between the Jas Roux ore-forming system and low-temperature active geothermal brines.
SNIP (Scopus, 2015): 0.700
IF (ISI, 2015): 1.326
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