Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Mottled pink, white, gray, and black; Lustre: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Indistinct; Specific gravity: 2.63–2.75

Formation & Geological History

Formed by the slow crystallization of magma below Earth's surface. It is a coarse-grained intrusive rock that can form over millions of years within the Earth's crust (plutons).

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stone, monuments, and as crushed stone for road base.

Geological Facts

Granite makes up a large portion 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 its 'salt and pepper' appearance and visible interlocking crystals of different colors. It is found globally in mountainous regions and continental shields. Look for hardness (it will scratch glass).

Identified on: 5/1/2026

Mode: Standard