igneous
Granite or granitic gneiss gravel
Crystalline quartz–feldspar–mica aggregate; possibly weathered granitic gneiss
AI-generated identification · may be incorrectTypically Mohs hardness 6–7, light gray to pink or cream, with a granular texture and vitreous quartz alongside white feldspar and dark mica/amphibole. No prominent cleavage as a rock, though feldspar and mica show mineral cleavage; specific gravity is about 2.6–2.8.
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Physical properties
Typically Mohs hardness 6–7, light gray to pink or cream, with a granular texture and vitreous quartz alongside white feldspar and dark mica/amphibole. No prominent cleavage as a rock, though feldspar and mica show mineral cleavage; specific gravity is about 2.6–2.8.
Formation & geological history
Formed by slow cooling of silica-rich magma deep underground, producing coarse interlocking crystals; if foliated, it may represent metamorphosed granite. Most granite formed during Precambrian–Phanerozoic geologic episodes and was later quarried and crushed for aggregate.
Uses & applications
Widely used as road base, railway ballast, drainage gravel, concrete aggregate, landscaping stone, and building or paving material; attractive pieces may be collected but are generally low value.
Geological facts
The hand specimen appears strongly weathered and may contain dark biotite/amphibole-rich inclusions or iron-oxide staining. Crushed granite is one of the most common aggregates because it is hard, durable, and resistant to abrasion.
Field identification & locations
Identify it by visible interlocking grains of gray translucent quartz, pale feldspar, and black mica/amphibole; a steel nail usually will not scratch it, while quartz can scratch glass. Common in gravel pits and glacial or alluvial deposits worldwide.
