igneous
Black-and-white granite
Granite, primarily quartz–feldspar–biotite aggregate
AI-generated identification · may be incorrectCoarse-grained, phaneritic texture with white/pink feldspar, translucent gray quartz, and black biotite or amphibole; hardness about 6–7, generally non-cleaved as a rock, with vitreous quartz and pearly feldspar luster. Typical specific gravity is 2.6–2.8.
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Physical properties
Coarse-grained, phaneritic texture with white/pink feldspar, translucent gray quartz, and black biotite or amphibole; hardness about 6–7, generally non-cleaved as a rock, with vitreous quartz and pearly feldspar luster. Typical specific gravity is 2.6–2.8.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep in the continental crust, commonly during Precambrian to Phanerozoic mountain-building events; the exact age cannot be determined visually.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building cladding; attractive polished pieces are collected but usually have modest value.
Geological facts
The visible interlocking crystals indicate slow underground cooling rather than volcanic eruption. Dark minerals may be biotite mica, hornblende, or both.
Field identification & locations
Identify it by its coarse interlocking grains, abundant light feldspar/quartz, and dark mica or amphibole, with no layers or vesicles; common worldwide in continental batholiths, including India, Brazil, Scandinavia, and North America.
