Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: typically mottled pink, white, gray, and black; Luster: vitreous to dull; Crystal structure: phaneritic (coarse-grained), crystalline; Cleavage: none (individual minerals like mica may show it); Specific gravity: 2.63 - 2.75

Formation & Geological History

Formed from the slow crystallization of magma below the Earth's surface (intrusive). Granites can be hundreds of millions to billions of years old and are typically found in the continental crust within mountain belts and cratons.

Uses & Applications

Used extensively in construction for countertops, floor tiles, paving stones, and memorial monuments due to its durability and resistance to weathering.

Geological Facts

Granite makes up much of the Earth's continental crust. Unlike basalt which is found on the ocean floor, granite is unique to Earth and has not been found in significant quantities on other planets.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and biotite mica. Common in states like New Hampshire (The Granite State) and mountain ranges like the Sierra Nevada.

Identified on: 4/16/2026

Mode: Standard