Quartzite

A hard rock, originally composed of sandstone, that fractures through individual silica grains rather than around them. Quartzite can be created by the tight cementation and compaction of the sandstone grains in sedimentary contexts (orthoquartzite), or through the metamorphoric distortion of the sandstone. The quality of quartzite is variable, from a sugary texture to smooth and glassy, but highly metamorphized quartzite can flake as easily as chert. Quartzite usually occurs in shades of gray, white, red, and brown, and can contain inclusions such as small, dark lignite particles (Lowery 2002). Massive beds of quartzite are found on the western slopes of the Maryland Blue Ridge, and smaller outcrops occur on the west side of the Chesapeake. It commonly occurs as cobbles along streams. Orthoquartzites from sources around the Chesapeake come in a wide variety of colors, but tend to be darker when freshly exposed, and often become lighter as they weather (Lowery 2002).