Sulvanite from Thorpe Hills, Utah¹

Sulvanite, Cu₃VS₄, has been identified from a prospect in Thorpe Hills, Utah. This is the fourth world occurrence and the second in the United States. The sulvanite forms cubic crystals up to 2.5 cm in size, with a definite bronze sheen on fresh fractures. Except where fractured, all samples are coated with a yellowish-green alteration product of volborthite.

The unit cell parameter determined by a least squares method is a₀ Å 5.3915. X-ray powder diffraction data agree very well with those listed for sulvanite from the Mercur District, Utah. Chemical analysis determined the unit cell content to be Cu_3.00 V_0.99 S_3.99. This is in excellent agreement with the theoretical unit cell content of Cu_3.00V_0.99S_3.99. The chemical analysis of the sulvanite is Cu 31.90, S 21.36 V 8.50 Samples from Thorpe Hills were compared with specimens from the type locality at the Edelweiss Mine, near Burra, South Australia. The vanadate alteration product of sulvanite at the Edelweiss Mine is vesignieite.

Sulvanite elements for both deposits are probably derived from underlying carbonaceous shales within the negative oxidation-potential zone below the water table. Migration of vanadium and copper ions occurred when faulting released confining pressure in the shale beds.