igneous
Weathered granite
Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, mottled pink-white-gray rock with glassy quartz, feldspar, and dark mica/amphibole; Mohs hardness about 6–7, vitreous to dull luster, interlocking crystals, no cleavage as a whole, specific gravity about 2.6–2.7.
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Physical properties
Coarse-grained, mottled pink-white-gray rock with glassy quartz, feldspar, and dark mica/amphibole; Mohs hardness about 6–7, vitreous to dull luster, interlocking crystals, no cleavage as a whole, specific gravity about 2.6–2.7.
Formation & geological history
An intrusive felsic igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to younger continental mountain-building events; this specimen is strongly weathered and rounded.
Uses & applications
Widely used as building stone, countertops, monuments, aggregate, and dimension stone; attractive polished pieces are collected but this example has modest value.
Geological facts
Pink coloration typically comes from potassium feldspar, while dark patches are biotite or hornblende and translucent grains are quartz.
Field identification & locations
Identify it by visible interlocking crystals and the quartz-feldspar-mica color pattern; common in continental shields, mountain ranges, glacial deposits, and stream gravels worldwide. A hand lens and streak, hardness, or acid tests help distinguish it from similar gneiss or weathered diorite.
