Granite

A coarse-grained rock that cooled slowly deep underground, made of quartz, feldspar and mica or hornblende.

Granite specimen — Photo: The stone gate, CC BY-SA 4.0, via Wikimedia Commons

How to identify granite

Speckled with interlocking grains you can see without a lens.
Glassy gray quartz plus pink or white blocky feldspar.
Black specks of mica or hornblende.
Hard, with no layering or banding.

Often confused with

Gneiss
Gneiss has the same minerals arranged in bands or stripes.
Compare side by side
Diorite
Diorite is black-and-white 'salt and pepper' with little or no quartz.
Compare side by side

Where it's found

Sierra Nevada, California
Stone Mountain, Georgia
Aberdeen, Scotland
Mount Rushmore, South Dakota

Uses

Countertops, monuments, paving and curling stones.

Rock tumbling

Great for tumbling.

Did you know?

Most Olympic curling stones are made of granite from Ailsa Craig, a tiny island off Scotland.

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