ABSTRACT
Because quartz itself is more or less colorless, small differences in protolith chemical composition can result in very different quartzite appearance. Quartzite color can be white or light-gray, the common colors of pure quartz, dark gray to black from admixture of graphite or more rarely tourmaline or magnetite, pink and red from hematite, and green from chlorite. Yellow, orange, and red-brown surface staining may result from the weathering of sulfides such as pyrrhotite or pyrite, carbonates such as ankerite at low metamorphic grade, or silicate minerals such as orthopyroxene in high-grade rocks. Because of surface staining, one often has to look closely at a fresh surface to see the abundant, glassy-clear, conchoidally fractured quartz grains.
