igneous
Coarse-grained granite or granitic pegmatite
Granite; chiefly quartz (SiO₂), feldspar, and mica/amphibole
AI-generated identification · may be incorrectHardness about 6–7; mottled white, pink, gray, and black, with a coarse crystalline texture and generally vitreous to dull luster. Visible interlocking crystals indicate no cleavage at the whole-rock scale, though feldspar and mica have cleavage.
Identified More igneous →
Explore Coarse-grained granite or granitic pegmatite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6–7; mottled white, pink, gray, and black, with a coarse crystalline texture and generally vitreous to dull luster. Visible interlocking crystals indicate no cleavage at the whole-rock scale, though feldspar and mica have cleavage.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep underground, commonly during Precambrian to Phanerozoic tectonic activity. The unusually large crystals may indicate pegmatitic growth or strongly coarse granite.
Uses & applications
Used as dimension stone, countertops, monuments, aggregate, and decorative landscaping rock; attractive pieces are collected but usually have modest value.
Geological facts
Pink areas are likely potassium feldspar, translucent gray areas quartz, and dark flakes or grains biotite mica and/or amphibole. The specimen appears weathered and somewhat pegmatitic, but a precise identification requires a fresh surface or thin section.
Field identification & locations
Identify it by its interlocking visible quartz, feldspar, and dark mafic minerals; it should not fizz with dilute acid and will scratch glass. Common worldwide in continental crust, especially shield regions and granite batholiths.
