igneous
Weathered granite (likely biotite granite)
Granite; chiefly quartz, feldspar, and biotite mica
AI-generated identification · may be incorrectCoarse-grained, mottled pink-brown and dark gray/black, with a dull weathered luster; visible interlocking crystals and no obvious foliation. Typical hardness is about 6–7 Mohs, with poor cleavage as a whole and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, mottled pink-brown and dark gray/black, with a dull weathered luster; visible interlocking crystals and no obvious foliation. Typical hardness is about 6–7 Mohs, with poor cleavage as a whole and specific gravity around 2.6–2.7.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep in the continental crust, commonly during Precambrian to Phanerozoic mountain-building events. The rounded shape and brown surface reflect weathering and abrasion.
Uses & applications
Widely used as dimension stone, countertops, flooring, monuments, aggregate, and landscaping rock; this small weathered piece has little commercial or jewelry value.
Geological facts
The pink coloration generally comes from potassium feldspar, while dark specks are commonly biotite or hornblende. Granite commonly develops rounded boulders through spheroidal weathering.
Field identification & locations
Identify it by its coarse interlocking texture and mixture of light quartz/feldspar with dark mica or amphibole; it should not fizz with dilute acid. Common worldwide, especially in exposed continental batholiths and granite quarries.
