igneous
Granite
Granite; predominantly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled white-gray rock with black mafic minerals; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no cleavage as a whole. The rounded surfaces indicate natural water or glacial erosion.
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Physical properties
Coarse-grained, speckled white-gray rock with black mafic minerals; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no cleavage as a whole. The rounded surfaces indicate natural water or glacial erosion.
Formation & geological history
Intrusive igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events. Exact age and source cannot be determined from the photograph.
Uses & applications
Widely used as dimension stone, countertops, monuments, flooring, crushed aggregate, and landscaping rock; attractive polished pieces have modest decorative and collecting value.
Geological facts
Granite’s visible crystals formed because the magma cooled slowly underground. Its composition overlaps with granodiorite, so precise identification may require a hand lens or thin-section analysis.
Field identification & locations
Identify by its coarse interlocking texture and contrasting quartz-feldspar-dark mineral pattern; it is common in continental crust, mountain belts, glacial deposits, and streambeds. These specimens appear weathered and rounded.
