igneous
Likely weathered granite or granitic pegmatite fragment
Granite/granitic rock; commonly quartz (SiO₂), feldspar, and biotite or amphibole
AI-generated identification · may be incorrectCoarse, mottled white-gray, brown, and black grains with a dull to slightly vitreous luster; individual crystals appear interlocking. Typical hardness is about 6–7 Mohs, with no dominant cleavage as a whole, though feldspar and mica cleave.
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Physical properties
Coarse, mottled white-gray, brown, and black grains with a dull to slightly vitreous luster; individual crystals appear interlocking. Typical hardness is about 6–7 Mohs, with no dominant cleavage as a whole, though feldspar and mica cleave.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep underground, generally during Precambrian to Phanerozoic intrusive events; the specimen appears naturally weathered or broken from an outcrop.
Uses & applications
Used widely as crushed aggregate, building stone, monuments, countertops, and decorative material; small ordinary fragments have little commercial value.
Geological facts
The pale grains are likely feldspar or quartz, while dark flakes may be biotite mica or amphibole. Exact identification requires a fresh surface, hand lens, and tests for quartz and feldspar.
Field identification & locations
Common worldwide in continental crust and exposed mountain belts; identify by visible interlocking crystals, hardness, and lack of layering or foliation. A photo alone cannot distinguish granite confidently from gneiss, diorite, or weathered pegmatite.
