igneous
Polished pegmatitic granite (likely graphic granite)
Coarse-grained granitic rock composed chiefly of quartz, feldspar, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7; mottled cream, white, tan, greenish, and black; glassy quartz, pearly feldspar, and dark mica. Interlocking crystals show no obvious cleavage as a rock, though feldspar and mica have cleavage; typical density is 2.6–2.8 g/cm³.
Identified More igneous →
Explore Polished pegmatitic granite (likely graphic granite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6–7; mottled cream, white, tan, greenish, and black; glassy quartz, pearly feldspar, and dark mica. Interlocking crystals show no obvious cleavage as a rock, though feldspar and mica have cleavage; typical density is 2.6–2.8 g/cm³.
Formation & geological history
Formed when silica-rich magma cooled slowly deep underground, allowing very large crystals to grow; pegmatitic varieties crystallized from late, water-rich melt, generally during Precambrian to Phanerozoic intrusive events.
Uses & applications
Used as decorative stone, countertops, facing stone, aggregate, and polished ornamental specimens; attractive pieces have modest collector value.
Geological facts
The white to translucent grains are quartz or feldspar, while black flakes or clusters are commonly biotite or hornblende. The rounded glossy surface appears polished or naturally water-worn.
Field identification & locations
Identify it by coarse interlocking crystals, abundant pale quartz/feldspar, and scattered dark mafic minerals; common in granitic terrains and stream gravels worldwide. A streak, acid, and hardness test can help distinguish it from altered or metamorphic rocks.
