Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, gray, and black. Luster: Vitreous to dull. Crystal Structure: Phaneritic (large, visible crystals). Cleavage: Varies by component mineral (e.g., perfect in mica, poor in quartz). Specific Gravity: 2.63 to 2.75.

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface (intrusive). Geological age spans from the Archean Eon to the Cenozoic. Typically forms in continental crust above subduction zones.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, 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 granite batholith. It is one of the hardest natural stones available for commercial use.

Field Identification & Locations

Identify by its 'salt and pepper' appearance and large interlocking crystals of quartz and feldspar. Found globally in mountainous regions and shield areas like the Canadian Shield or the Appalachians.

Identified on: 4/25/2026

Mode: Standard