igneous
Flecked granite pegmatite
Granitic rock composed mainly of quartz, alkali feldspar, plagioclase, and dark biotite/amphibole
AI-generated identification · may be incorrectCoarse-grained, pale gray to cream matrix with glassy quartz, blocky feldspar, and black mica or amphibole. Hardness is approximately 6–7 Mohs; nonfoliated, granular texture, vitreous quartz luster, and little or no cleavage as a whole.
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Physical properties
Coarse-grained, pale gray to cream matrix with glassy quartz, blocky feldspar, and black mica or amphibole. Hardness is approximately 6–7 Mohs; nonfoliated, granular texture, vitreous quartz luster, and little or no cleavage as a whole.
Formation & geological history
Formed when silica-rich magma cooled slowly deep in the crust, allowing large interlocking crystals to grow; typical intrusive ages range from Precambrian to recent geologic provinces. The exact locality and age cannot be determined from the photograph.
Uses & applications
Used as dimension stone, countertops, aggregate, monuments, and building stone; attractive pieces are collected, though this specimen appears mainly educational rather than gem-grade.
Geological facts
The dark minerals are likely biotite or hornblende, while translucent grains are quartz. A true pegmatite would generally have exceptionally large crystals; this may instead be ordinary coarse granite.
Field identification & locations
Identify it by interlocking light quartz/feldspar grains and scattered black minerals, with no layering or foliation. Common in continental mountain belts and exposed plutons worldwide; a glassy quartz grain scratches glass, while feldspar shows cleavage.
