igneous
Black-and-white pegmatitic granite
Granite, chiefly quartz–feldspar–biotite; possibly orbicular or graphic pegmatite
AI-generated identification · may be incorrectCoarse, contrasting white feldspar/quartz and black biotite or amphibole; vitreous to pearly luster, interlocking crystalline texture, Mohs hardness about 6–7, no obvious cleavage on the broken surface, and specific gravity roughly 2.6–2.8.
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Physical properties
Coarse, contrasting white feldspar/quartz and black biotite or amphibole; vitreous to pearly luster, interlocking crystalline texture, Mohs hardness about 6–7, no obvious cleavage on the broken surface, and specific gravity roughly 2.6–2.8.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep underground, commonly during Precambrian to Phanerozoic mountain-building events; the specimen appears weathered or cut from a larger mass.
Uses & applications
Used as dimension stone, countertops, monuments, aggregate, and decorative material; attractive pieces are collected but usually have modest value.
Geological facts
The white component is likely feldspar and quartz, while the black component is probably biotite mica or hornblende. Exact identification requires a fresh surface, hardness testing, and ideally petrographic or chemical analysis.
Field identification & locations
Look for visible interlocking grains, white feldspar/quartz, and black mafic minerals; granite is widespread in continental crust and occurs worldwide, especially in mountain belts and shield regions.
