igneous
Pegmatitic granite
Coarse-grained granite, chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled gray, white, brown, and black with a granular texture and vitreous to dull luster. Interlocking crystals show no obvious cleavage as a rock, though feldspar and mica have cleavage.
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Physical properties
Hardness about 6–7 Mohs; mottled gray, white, brown, and black with a granular texture and vitreous to dull luster. Interlocking crystals show no obvious cleavage as a rock, though feldspar and mica have cleavage.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep underground, likely during a Precambrian or younger continental event; the specimen may represent weathered or vein-related pegmatitic granite.
Uses & applications
Used as dimension stone, countertops, aggregate, monuments, and landscaping; attractive pieces are collected but generally have low gem value.
Geological facts
Large visible crystals indicate slow cooling, while the dark grains are likely biotite or hornblende and the pale grains feldspar or quartz.
Field identification & locations
Identify it by its coarse interlocking quartz-feldspar-mica texture, lack of layering, and inability to scratch with a steel nail. Common in continental mountain belts and exposed batholiths.
