metamorphic
Quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly crystalline SiO₂, possibly with iron-oxide staining and minor feldspar or mica
AI-generated identification · may be incorrectTypically Mohs hardness 7, white to gray with rusty red-brown patches, and a vitreous to sugary luster. It has interlocking quartz grains, poor cleavage, and conchoidal to irregular fracture; exact identification would benefit from a fresh break and hardness test.
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Physical properties
Typically Mohs hardness 7, white to gray with rusty red-brown patches, and a vitreous to sugary luster. It has interlocking quartz grains, poor cleavage, and conchoidal to irregular fracture; exact identification would benefit from a fresh break and hardness test.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism. It may range from Precambrian to younger ages, depending on its source terrain.
Uses & applications
Used as durable aggregate, building and paving stone, landscaping material, and occasionally as a decorative or lapidary stone.
Geological facts
Quartzite commonly breaks across, rather than around, its original sand grains; unlike sandstone, individual grains are difficult to scratch out. The reddish coloration commonly comes from hematite or other iron oxides.
Field identification & locations
Common in metamorphic mountain belts worldwide, including the Appalachians, Rocky Mountains, Alps, and Scandinavian mountains. If a steel file cannot scratch it and the grains appear fused, quartzite is likely; the image alone cannot exclude quartz-rich sandstone or massive quartz.
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