igneous
Granite (likely biotite or hornblende granite)
Coarse-grained felsic intrusive rock; chiefly quartz (SiO₂), plagioclase and potassium feldspar, with minor biotite/hornblende
AI-generated identification · may be incorrectLight gray, massive, granular texture with dark specks and scattered pinkish feldspar; likely hardness 6–7 Mohs, vitreous to dull luster, interlocking crystals, and no cleavage as a whole. The rounded shape and surface smoothing indicate stream or glacial abrasion.
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Physical properties
Light gray, massive, granular texture with dark specks and scattered pinkish feldspar; likely hardness 6–7 Mohs, vitreous to dull luster, interlocking crystals, and no cleavage as a whole. The rounded shape and surface smoothing indicate stream or glacial abrasion.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the continental crust, commonly during Precambrian to Phanerozoic plutonic events; the specific age cannot be determined visually.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving aggregate, and construction fill; this rounded field specimen has little commercial value.
Geological facts
Granite’s visible grains record slow cooling underground. Its pale color indicates abundant quartz and feldspar, while dark grains are likely biotite or amphibole.
Field identification & locations
Identify it by its visible interlocking quartz-feldspar grains, light color, and dark mica/amphibole flecks; distinguish it from uniform quartzite by the varied mineral grains. Common in continental mountain belts and glacial or river gravels.
