metamorphic
Weathered quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly quartz (SiO₂), possibly with feldspar, mica, and iron-oxide staining
AI-generated identification · may be incorrectWhite to gray, granular and strongly weathered, with dull to weakly glassy luster; quartz hardness is about Mohs 7, no obvious cleavage, and quartzite has an interlocking crystalline texture. The rounded shape and surface discoloration indicate abrasion and weathering.
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Physical properties
White to gray, granular and strongly weathered, with dull to weakly glassy luster; quartz hardness is about Mohs 7, no obvious cleavage, and quartzite has an interlocking crystalline texture. The rounded shape and surface discoloration indicate abrasion and weathering.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure, commonly during mountain-building; its exact geological age cannot be determined from the photograph. It may have later been transported as a river or glacial cobble.
Uses & applications
Used as crushed stone, aggregate, road material, riprap, and building or decorative stone; attractive dense pieces may be polished, though this specimen appears ordinary and heavily weathered.
Geological facts
Quartzite commonly resists scratching by a steel knife and typically breaks across quartz grains rather than around them. A vinegar test is generally negative, helping distinguish it from limestone or marble.
Field identification & locations
Common in metamorphic mountain belts and stream gravels worldwide. Confirm by checking that grains are fused, the rock does not fizz with dilute acid, and a steel tool fails to scratch it; the image alone cannot exclude hard sandstone or light-colored granite.
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