igneous
Granite (likely pegmatitic granite)
Felsic intrusive igneous rock, primarily quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, pale gray-white with black mica or amphibole; interlocking crystals, vitreous quartz luster, and Mohs hardness about 6–7. Feldspar cleavage may be visible, while quartz lacks cleavage.
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Physical properties
Coarse-grained, pale gray-white with black mica or amphibole; interlocking crystals, vitreous quartz luster, and Mohs hardness about 6–7. Feldspar cleavage may be visible, while quartz lacks cleavage.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic plutonic activity. The specimen may come from a pegmatitic zone if its crystals are unusually large.
Uses & applications
Used as building and dimension stone, countertops, monuments, aggregate, and decorative material; attractive pieces are collected as mineral specimens.
Geological facts
Granite’s visible crystals record slow underground cooling. Black grains are commonly biotite mica or hornblende, while white grains are feldspar and translucent grains are quartz.
Field identification & locations
Identify it by its speckled, interlocking texture and inability to scratch with a steel knife; dilute acid generally causes no reaction. Common worldwide in continental mountain belts and exposed batholiths.
