Quartzite

**Characteristics and Origin**:
– Quartzite is a hard rock with an interlocking mosaic of quartz crystals.
– The surface of quartzite is grainy and glassy in appearance.
– Quartzite must contain at least 80% quartz by volume for British Geological Survey classification.
– Quartzite is formed when sandstone undergoes regional metamorphism, with quartz grains recrystallizing.
– Recrystallized quartz grains in quartzite are roughly equal in size, forming a granoblastic texture.

**Geographical Occurrence**:
– Quartzite formations can be found in regions across the United States, including Pennsylvania, South Dakota, and Utah.
– Notable locations with quartzite include the Morenci Copper Mine in Arizona and the La Cloche Mountains in Ontario, Canada.
– Quartzite deposits are also present in Ireland, the United Kingdom, and continental Europe.
– Precambrian basement rock in western North America features Paleoproterozoic quartzite-rhyolite successions.

**Uses**:
– Quartzite has historical uses in prehistoric stone tools and contemporary applications as decorative dimension stone.
– It is utilized in highway construction as crushed stone and as a source of silica for silicon production.
– Quartzite’s hardness and resistance make it valuable for various industrial applications.
– Increasingly used for kitchen countertops due to its durability and stain resistance.

**Relationships with Other Rocks**:
– Quartzite is derived from the metamorphism of quartz sandstone.
– Orthoquartzite and metaquartzite describe different levels of cementation and metamorphism in quartzite.
– The distinction between orthoquartzite and quartz sandstone lies in the cementation level.
– As metamorphism progresses, quartz grains in quartzite undergo recrystallization, leading to different textures.

**Safety and Etymology**:
– Quartzite, being a form of silica, poses risks in workplaces due to hazardous silica dust.
– Activities like cutting, grinding, and polishing quartzite can release respirable crystalline silica.
– Workers involved in quartzite processing should take precautions to minimize exposure to silica dust.
– The term ‘quartzite’ originates from the German word ‘Quarzit’.https://en.wikipedia.org/wiki/Quartzite