Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Pink, orange, gray, and black mottled pattern; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: None (fractures); Specific Gravity: 2.63 - 2.75

Formation & Geological History

Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen appears water-worn, likely found in a riverbed or glacial deposit. Can range from Precambrian to Cenozoic in age.

Uses & Applications

Used extensively in construction for countertops, floor tiles, and monuments. Also used as crushed stone for road base and aggregate.

Geological Facts

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

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. Commonly found in mountainous regions or areas with exposed continental shields.

Identified on: 4/25/2026

Mode: Standard