Secondary phosphates from bingham, utah¹

Turquois, vivianite, and wavellite have been found as secondary minerals in the Utah copper mine, Bingham, Utah. Dense, bluish turquois veinlets up to an inch wide with associated pyrite are present in quartzite and granite porphyry. Spectrochemical analysis shows less than 0.01 per cent iron, indicating that the turquois is the pure aluminum end member of the series turquois-chalcosiderite. Well-developed elongated crystals of vivianite up to 5 cm in length are found along open cracks in silicified limestone. They are deep purple; when broken, the centers of the crystals are colorless and transparent but upon exposure rapidly oxidize to a deep purple. Analysis indicates a composition of Fe_2.98Mg_0.02(PO₄)₂·8H₂O. Pale yellow wavellite occurs as radial botryoidal crusts in open cracks and vugs in granite porphyry and quartzite.

The three phosphates occur in zones along the north edge of the pit with vivianite farthest west, turquois in the center, and wavellite toward the east. The phosphate is believed to have been derived from the fossiliferous Tilden Limestone. The positions of vivianite and turquois appear to correspond to the iron and copper zones of the pit. Aluminum was likely derived from the aluminum silicate minerals of the stock. X-ray and differential thermal analysis data are in good agreement with those previously published for these minerals. Infrared spectra shows characteristic curves expected in the 2.5-3 and 9-10 micron regions.