What Type of Metamorphic Rock Is Formed From Sand?

Quartzite

• Quartzite is a hard metamorphic rock that is usually white to gray in color, although mineral impurities can color the rock yellow, orange, pink or red. Unlike the rough textured sandstone from which quartzite is derived, quartzite has a smooth texture. This is because when the rock breaks, it does so across the grains rather than around them. Orthoquartzite is derived from very pure sandstone with spherical grains of quartz cemented together with silica. This particular variety of quartzite can be as much as 99 percent pure silicon oxide.

Uses

• Because quartzite is so hard (it is harder than both granite and limestone), it has not been quarried as extensively as other stones. However, demand for the stone has been increasing in the construction industry, particularly because it splits into flat planes. Quartzite is also used to produce industrial-quality silica sand and in the production of silicon carbide.

Formation

• Quartzite more often than not has formed during mountain-building episodes where continental plates have collided with each other. Because the mineral is so compact and resilient, quartzite is exceptionally resistant to erosion and weathering. This accounts for the rock being frequently seen as outcrops sticking out from its surroundings.

Occurrence

• In the United States, quartzite can be found in areas where there has been forceful metamorphism. It is commonly found in the Appalachian mountain ridges, especially in the mountain crests. It is also found in Montana, Arizona, South Dakota, Minnesota, Idaho and New York. Quartzite is a poor bedrock because it is not good at bearing soil, with the result that it is usually found close to the surface.