igneous
Granite
Granite; chiefly quartz (SiO₂), feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse-grained, speckled gray-white rock with black mafic minerals; typically Mohs 6–7, vitreous to dull luster, interlocking crystals, and no cleavage as a whole. The specimen appears naturally fractured and unpolished.
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Physical properties
Coarse-grained, speckled gray-white rock with black mafic minerals; typically Mohs 6–7, vitreous to dull luster, interlocking crystals, and no cleavage as a whole. The specimen appears naturally fractured and unpolished.
Formation & geological history
Intrusive felsic igneous rock formed by slow cooling of silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events. Exact age and locality cannot be determined from the image.
Uses & applications
Widely used as dimension stone, countertops, monuments, aggregate, and building material; small pieces are mainly educational or decorative specimens.
Geological facts
Visible grains indicate plutonic cooling rather than volcanic eruption. Dark bands or patches may reflect biotite, hornblende, or compositional variation toward granodiorite.
Field identification & locations
Identify by coarse interlocking grains, abundant pale feldspar/quartz, and scattered black mica or amphibole; distinguish from gneiss if the dark minerals are not strongly layered or foliated. Common worldwide in continental mountain belts.
