Definition Of Quartzite

The main chemical component of quartzite is quartz-SiO₂. Quartzite generally has a massive structure, a granular metamorphic texture, and appears as a crystalline aggregate. Quartz also comes in a wide variety of colors, with common colors including green, gray, yellow, brown, orange-red, white, blue, purple, and red.

The protolith of quartzite can be: monomineralic quartz sandstone, argillaceous and calcareous quartz sandstone, colloidally deposited siliceous rocks (including siliceous rocks formed by the dissolution and redeposition of terrigenous clasts and siliceous rocks associated with volcanic exhalations), and deep-sea radiolarian chert, etc.

Quartzites formed from different protoliths can be distinguished based on their structure, degree of metamorphism, accessory minerals, rock associations, and occurrence. For example, quartzite formed from monomineralic quartz sandstone has a coarser grain size, often exhibits a typical equilibrium mosaic structure, and contains more accessory minerals such as zircon. Quartzite formed from siliceous rocks, even under high-grade metamorphism, rarely has mineral grains larger than 0.2 millimeters, and exhibits a serrated intergrowth structure, generally without accessory minerals.