igneous
Granite
Granite, primarily quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled gray-white rock with glassy quartz, light feldspar, and dark mica or amphibole; hardness about 6–7 Mohs, granular crystal texture, generally no cleavage as a whole, and specific gravity about 2.63–2.75.
Identified More igneous →
Explore Granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse-grained, speckled gray-white rock with glassy quartz, light feldspar, and dark mica or amphibole; hardness about 6–7 Mohs, granular crystal texture, generally no cleavage as a whole, and specific gravity about 2.63–2.75.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma cooled slowly deep underground, allowing visible crystals to grow. Most granite formed during Precambrian to Phanerozoic mountain-building events, though its exact age requires laboratory analysis.
Uses & applications
Widely used for countertops, monuments, building stone, paving, and aggregate; attractive polished pieces are also collected, though ordinary hand specimens have little commercial value.
Geological facts
Its interlocking crystals give granite excellent durability and resistance to abrasion. The dark minerals may indicate biotite-rich granite, granodiorite, or another closely related granitoid.
Field identification & locations
Identify it by its coarse, visible quartz-feldspar-mica mixture and lack of layering or foliation; unlike gneiss, it is not strongly banded. Common in continental mountain belts and exposed batholiths worldwide.
