Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Salt and pepper (mottled gray, white, pink, and black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Distinct in feldspar components; Specific gravity: 2.63 - 2.75

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface. It is an intrusive igneous rock typical of continental crust, often dating back hundreds of millions to billions of years.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stone, curbing, and monuments due to its durability and aesthetic appeal.

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 by its coarse grain size and interlocking crystals of quartz (clear/gray), feldspar (white/pink), and mica (black/shiny). Commonly found in mountain ranges and glacial deposits.

Identified on: 4/14/2026

Mode: Standard