Quartz

Quartz is composed of oxygen and silica combined in a ratio of 2: 1. This mineral is hard, durable, weather-resistant, and relatively common.  Quartz crystals formed as hot waters percolated through fractured rock in the Ouachita Mountains some 245 million years ago.  Chemically pure sources of quartz are in much demand by industry as a source of the raw chemical feedstock for the manufacture of quartz wafers, silicon metal, glass, fused quartz, and optical fiber.  Arkansas has the most significant economically valuable deposits of high-quality quartz in the United States.