igneous
Coarse-grained granite
Granite, chiefly quartz (SiO₂), potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 (individual minerals); pink, white, gray, and black crystals with a coarse phaneritic texture and generally vitreous to pearly luster. No obvious foliation; feldspar commonly shows cleavage, while quartz lacks cleavage.
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Physical properties
Hardness about 6–7 (individual minerals); pink, white, gray, and black crystals with a coarse phaneritic texture and generally vitreous to pearly luster. No obvious foliation; feldspar commonly shows cleavage, while quartz lacks cleavage.
Formation & geological history
Intrusive igneous rock formed by slow cooling and crystallization of silica-rich magma deep in the continental crust, typically during Precambrian to younger mountain-building events. The specimen may also be weathered or hydrothermally altered, judging from its rough, iron-stained surface.
Uses & applications
Widely used as dimension stone, countertops, monuments, tiles, crushed aggregate, and decorative landscaping material; attractive polished pieces are collectible but usually inexpensive.
Geological facts
Pink coloration commonly comes from potassium feldspar, gray translucent grains are quartz, and dark flakes are biotite or amphibole. Granite is the coarse-grained intrusive equivalent of rhyolite.
Field identification & locations
Identify it by visible interlocking crystals of pink/white feldspar, gray quartz, and black mica, unlike sandstone or foliated gneiss. Common worldwide in continental shields and mountain ranges, including India, Brazil, Scandinavia, and North America.
