igneous
Granite
Coarse-grained felsic intrusive igneous rock; chiefly quartz, alkali feldspar, plagioclase, and biotite/muscovite mica
AI-generated identification · may be incorrectTypically hardness 6–7 Mohs, light gray to pink with black mica, vitreous quartz and pearly mica luster, granular texture, and no cleavage as a whole (individual minerals may cleave). The specimen appears weathered and coarse-grained, with reflective mica flakes.
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Physical properties
Typically hardness 6–7 Mohs, light gray to pink with black mica, vitreous quartz and pearly mica luster, granular texture, and no cleavage as a whole (individual minerals may cleave). The specimen appears weathered and coarse-grained, with reflective mica flakes.
Formation & geological history
Forms when silica-rich magma cools slowly deep underground, allowing large interlocking crystals to develop; most examples formed during Precambrian to Phanerozoic mountain-building events. Exact age cannot be determined from the photograph.
Uses & applications
Widely used for countertops, monuments, buildings, paving, crushed stone, and aggregate; attractive hand specimens are collected but usually have modest value.
Geological facts
Granite’s visible crystals provide a classic example of an intrusive igneous texture. Dark patches may be biotite or amphibole, while bright reflective flakes are mica.
Field identification & locations
Identify it by its coarse, interlocking quartz-feldspar-mica grains and lack of layering or pores; distinguish it from gneiss if strong mineral banding is present. Common worldwide in continental shields, batholiths, and mountain belts.
