igneous
Pegmatitic granite
Granite, quartz–feldspar–mica assemblage
AI-generated identification · may be incorrectCoarse-grained, mottled white, pink, gray, and black; interlocking quartz and feldspar with dark mica or amphibole. Hardness is approximately 6–7 Mohs, vitreous to pearly luster, no obvious cleavage as a whole, and specific gravity about 2.6–2.8.
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Physical properties
Coarse-grained, mottled white, pink, gray, and black; interlocking quartz and feldspar with dark mica or amphibole. Hardness is approximately 6–7 Mohs, vitreous to pearly luster, no obvious cleavage as a whole, and specific gravity about 2.6–2.8.
Formation & geological history
A slowly cooled intrusive igneous rock formed from silica-rich magma, likely in a granitic pluton or pegmatite zone. Its exact geological age cannot be determined from the photograph and may range from Precambrian to younger.
Uses & applications
Used as dimension stone, countertops, aggregate, monuments, and landscaping material; attractive feldspar, quartz, or mica crystals may have modest collector value.
Geological facts
The unusually large crystals suggest pegmatitic texture, produced when residual magma cools slowly and becomes enriched in water and incompatible elements.
Field identification & locations
Identify it by visible coarse interlocking crystals: translucent gray quartz, pink/white feldspar, and black mica. Common worldwide in continental mountain belts; a typical hand specimen is worth about $5–$30, more if it contains exceptional crystals or rare minerals.
