igneous
Granite
Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled gray-and-white rock with interlocking crystals; quartz has Mohs hardness 7, feldspars 6–6.5. It has a glassy-to-pearly quartz luster, blocky feldspar cleavage, no foliation, and typical specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, speckled gray-and-white rock with interlocking crystals; quartz has Mohs hardness 7, feldspars 6–6.5. It has a glassy-to-pearly quartz luster, blocky feldspar cleavage, no foliation, and typical specific gravity around 2.6–2.7.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events; the exact age cannot be determined from the image.
Uses & applications
Widely used as crushed aggregate, road stone, dimension stone, countertops, monuments, and building facades; attractive polished pieces may be collected but usually have modest value.
Geological facts
The specimen appears strongly weathered or fractured, with dark minerals forming irregular patches rather than clear layering. Similar-looking rocks may include granodiorite, gneiss, or quartz-rich metamorphic rock.
Field identification & locations
Identify granite by visible interlocking quartz and feldspar grains, lack of sedimentary layers, and a hard, scratch-resistant surface; common worldwide, especially in continental mountain belts and shield regions.
