Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white, grey, and black). Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained). Cleavage: None (fractures). Specific gravity: 2.63 - 2.75.

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface (intrusive). It is a major component of the continental crust, with ages ranging from billions of years to more recent tectonic events.

Uses & Applications

Extensively used in construction (countertops, tiles, paving), monuments, and as crushed stone for road base and railroad ballast.

Geological Facts

Granite is one of the hardest and most common rocks in the world. Famous landmarks like Mount Rushmore and the Egyptian pyramids contain various types of granite structures.

Field Identification & Locations

Identify in the field by its coarse-grained interlocking crystals and lack of foliation. Common in mountain ranges and continental shields. Look for visible flecks of quartz, feldspar, and mica.

Identified on: 4/17/2026

Mode: Standard