igneous
Granite
Phaneritic felsic intrusive igneous rock; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled white, gray, and black appearance with vitreous quartz and feldspar luster; individual mineral hardness is about Mohs 6–7, with no strong cleavage as a whole. Typical density is 2.6–2.8 g/cm³.
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Physical properties
Coarse-grained, speckled white, gray, and black appearance with vitreous quartz and feldspar luster; individual mineral hardness is about Mohs 6–7, with no strong cleavage as a whole. Typical density is 2.6–2.8 g/cm³.
Formation & geological history
Forms when silica-rich magma cools slowly deep underground, allowing visible crystals to grow; specimens commonly range from Precambrian to much younger Phanerozoic ages.
Uses & applications
Widely used for countertops, monuments, building stone, paving, aggregate, and ornamental landscaping; this rounded specimen is mainly suitable for collecting or decoration.
Geological facts
Its interlocking crystals distinguish it from rhyolite, which has similar chemistry but a fine-grained texture. Dark minerals are usually biotite mica and/or amphibole.
Field identification & locations
Identify it by visible quartz and feldspar crystals in a randomly interlocking texture, with scattered dark mica or amphibole. Common worldwide in continental batholiths, including the Sierra Nevada, New England, Scandinavia, and India.
