igneous
Granite-like pegmatitic rock
Coarse-grained granitoid, likely quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectLight gray to white with black mica or amphibole; granular texture and vitreous to pearly luster. Typical hardness is about 6–7 Mohs, with no strong cleavage as a whole, though feldspar and mica show cleavage; exact identification requires testing.
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Physical properties
Light gray to white with black mica or amphibole; granular texture and vitreous to pearly luster. Typical hardness is about 6–7 Mohs, with no strong cleavage as a whole, though feldspar and mica show cleavage; exact identification requires testing.
Formation & geological history
Likely crystallized slowly from silica-rich magma, producing interlocking crystals; commonly formed in continental crust, generally Precambrian to Phanerozoic in age. The image alone cannot establish a precise age or locality.
Uses & applications
Used as building and decorative stone when present in large masses; small fragments have little industrial or jewelry value and are mainly teaching or collecting specimens.
Geological facts
The contrasting white, gray, and black grains are consistent with feldspar, quartz, and biotite/amphibole. It could alternatively be a light metamorphic rock such as gneiss or amphibolite-bearing material.
Field identification & locations
Look for visible interlocking quartz (glassy gray), feldspar (white or pink), and black mica (flaky) grains; a glass-scratch test and fresh broken surface help distinguish it from similar rocks. Common worldwide, especially in shield and mountain regions.
