Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: typically pink, white, gray, or black phaneritic grains; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained) interlocking crystals; Specific gravity: 2.65 to 2.75.

Formation & Geological History

Formed from the slow crystallization of magma below the Earth's surface (intrusive). Most granite was formed during the Precambrian era or more recently in continental crust thickening events.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, monuments, and as a structural building material. It is also a popular rock for gravel and road base.

Geological Facts

Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith in the Black Hills of South Dakota.

Field Identification & Locations

Identify in the field by looking for a 'salt and pepper' appearance with visible crystals of quartz (glassy), feldspar (pink/white), and mica (shiny black flakes). It is found worldwide in mountainous regions and continental shields like the Canadian Shield.

Identified on: 4/26/2026

Mode: Standard