metamorphic
Quartz-rich rock, likely quartzite or milky quartz
Quartz (SiO₂); probable quartzite if the grains are interlocked
AI-generated identification · may be incorrectWhite to pale gray, granular, and nonmetallic with a vitreous-to-dull luster; quartz hardness is Mohs 7, with no cleavage and conchoidal fracture. The specimen appears fine-grained and moderately rounded, but the photo cannot confirm texture or density.
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Physical properties
White to pale gray, granular, and nonmetallic with a vitreous-to-dull luster; quartz hardness is Mohs 7, with no cleavage and conchoidal fracture. The specimen appears fine-grained and moderately rounded, but the photo cannot confirm texture or density.
Formation & geological history
Quartzite forms when quartz sandstone is recrystallized during metamorphism, commonly during mountain building; its age depends on the source formation and may range from Precambrian to younger. If it is massive milky quartz, it instead formed from silica-rich hydrothermal fluids in veins.
Uses & applications
Quartzite is used as crushed stone, aggregate, building and paving stone, and occasionally as decorative material. Clear or attractive quartz may be collected, but this opaque piece has limited gem value.
Geological facts
It should scratch ordinary glass and resist scratching by a steel knife. A streak test is white; dilute acid normally produces no reaction unless carbonate minerals are present.
Field identification & locations
Common in metamorphic terrains and quartz veins worldwide, including Brazil, India, the United States, and Scandinavia. Inspect a fresh surface: interlocking grains suggest quartzite, while glassy translucent masses suggest vein quartz.
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