metamorphic
Weathered quartz-rich rock, likely quartzite
Quartzite (predominantly microcrystalline quartz, SiO₂), possibly quartz-rich sandstone or milky-vein quartz
AI-generated identification · may be incorrectPale gray to cream, massive and granular with a dull to vitreous luster; quartz has Mohs hardness 7, no cleavage, and white streak. The specimen appears strongly weathered, with iron-oxide staining and uneven fracture surfaces.
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Physical properties
Pale gray to cream, massive and granular with a dull to vitreous luster; quartz has Mohs hardness 7, no cleavage, and white streak. The specimen appears strongly weathered, with iron-oxide staining and uneven fracture surfaces.
Formation & geological history
Likely formed when quartz-rich sandstone recrystallized under heat and pressure during regional metamorphism; its exact geological age cannot be determined from the image. If it is vein quartz instead, it formed from silica-rich hydrothermal fluids filling a fracture.
Uses & applications
Quartzite is used as crushed aggregate, road stone, building stone, and occasionally as decorative stone; attractive pieces may be collected but this example has modest commercial value.
Geological facts
Quartzite commonly breaks across quartz grains rather than around them and can be tougher than sandstone. Brown coloration is typically caused by oxidized iron minerals.
Field identification & locations
Look for grains fused into a hard, sugary or glassy mass, abundant quartz, and resistance to scratching by a steel knife; a glass plate test is more reliable, as quartz should scratch glass. Common in metamorphic belts worldwide.
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