Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Gray, salt-and-pepper, pink, or white; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained), equigranular; Cleavage: None (though constituent minerals have cleavage); Specific Gravity: 2.63 - 2.75

Formation & Geological History

Formed through the slow crystallization of magma below the Earth's surface (intrusive). Most granites are associated with continental crust and are from the Precambrian to Cenezoic eras.

Uses & Applications

Widely used in construction for countertops, floor tiles, paving stone, monuments, and as a structural stone due to its durability and resistance to weathering.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. It is often found in the core of mountain ranges like the Sierra Nevada or the Rockies. Famous landmarks like Mount Rushmore are carved into granite batholiths.

Field Identification & Locations

Identify in the field by its visible interlocking crystals of quartz (clear/gray), feldspar (white/pink), and mica (black/shiny). It is ubiquitous in continental mountainous regions. Collectors look for large crystals or unique coloration.

Identified on: 5/16/2026

Mode: Standard