Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white, grey, black, pink). Luster: Vitreous to dull. Crystal structure: Phaneritic (medium to coarse-grained) interlocking crystals. Specific gravity: 2.63 - 2.75.

Formation & Geological History

Formed through the slow crystallization of silica-rich magma below the Earth's surface (intrusive). Geological age varies from Precambrian to Cenozoic depending on the tectonic setting.

Uses & Applications

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

Geological Facts

Granite makes up the majority of Earth's continental crust. Mount Rushmore is carved into a granite batholith. It contains natural traces of radioactive isotopes like uranium.

Field Identification & Locations

Identify by its 'salt and pepper' look where you can see individual mineral grains of quartz (glassy), feldspar (opaque white/pink), and mica/amphibole (black flakes). Found in large mountain ranges and shield areas globally.

Identified on: 5/15/2026

Mode: Standard