A geochemical study of the barite deposits of Mineral County, Nevada

Abstract

The barite deposits of Mineral County, Nevada are localized along the intersection of the Walker Lane and the Antler Orogenic belts. There are two distinct types of barite deposits within Mineral County, bedded deposits and vein deposits. The bedded barite deposits occur in the Ordovician Palmetto formation as barite beds that, are conformable to the host rocks. These beds can be massive and of commercial grade. The vein deposits occur in a variety of host rocks and are always discordant to the host. These are epithermal appearing veins and they may also be of ore grade. Strontium analyses made on purified barites of both types showed that the barite of the vein deposits contains significantly more strontium than the barites of the bedded deposits. The average strontium content of the bedded barites was 28S ppm while the average strontium content for the vein deposits was 1,733 ppm. No selenium or lead was detected in any of the barite samples from either type of deposit. Sulfur isotopic analyses made on samples from both types of deposit have shed some light on the possible genesis of the deposits. The bedded deposits appear to be syngeneic with the sulfate being derived from Ordovician oceanic sulfate. The vein deposits appear to be epithermal with an equilibration between the barite and the associated sulfide minerals being replied at 170° C. The sulfate source for the barite veins may have been the underlying Ordovician barite bearing sediments.