igneous
Weathered granite pebble
Granite, typically quartz + feldspar + mica; approximate composition varies
AI-generated identification · may be incorrectMedium- to coarse-grained, pinkish-gray, granular rock with dull to slightly sparkling luster; interlocking crystals, no prominent cleavage as a whole. Hardness is about 6–7 Mohs and specific gravity about 2.63–2.75.
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Physical properties
Medium- to coarse-grained, pinkish-gray, granular rock with dull to slightly sparkling luster; interlocking crystals, no prominent cleavage as a whole. Hardness is about 6–7 Mohs and specific gravity about 2.63–2.75.
Formation & geological history
An intrusive felsic igneous rock formed by slow cooling of silica-rich magma deep underground, commonly during Precambrian to Phanerozoic mountain-building events; this specimen was later rounded by stream or glacial erosion.
Uses & applications
Used extensively as building stone, countertops, monuments, aggregate, and decorative material; attractive polished pieces are collected but this pebble has minimal commercial value.
Geological facts
Pink areas are likely potassium feldspar, gray translucent grains are quartz, and dark grains are biotite or amphibole. Its rounded shape and smooth weathering indicate transport or prolonged surface abrasion.
Field identification & locations
Identify it by visible interlocking pink/white feldspar, gray quartz, and black mica, unlike uniform basalt or layered sedimentary rocks; common worldwide in continental crust, especially riverbeds and glacial deposits.
