Experimental and field studies of scheelite in tactite deposits of the Stormy Day mine, Pershing County, Nevada

Abstract

Field work consisted of mapping and describing the Stormy Day mine in the Hooker mining district of Pershing County, Nevada, and a twelve square mile area surrounding the mines. The Stormy Day mine is a small contact metamorphic scheelite deposit, formed during the intrusion of Cretaceous granodiorite into Triassic- Jurassic limestone sediments. Mineral relationships in samples from the mines were used for comparison with experimental results to determine the geological applicability of laboratory work. High pressure-temperature experiments were performed to investigate possible genetic relationships between scheelite and calcium silicate minerals in which scheelite was formed from a tungsten source (H2WO4, W03, Na2WO4. 2H2O, and Na2WO4) and several calcium silicates which are commonly associated with scheelite in tactite deposits. Calcium silicates used in experiments were wollastonite, sphene, diopside, hedenbergite, and plagioclase. Calcite was used as a calcium source in some experiments. Effects of high-CO^ environments were also investigated.