Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (white, grey, and black) with some yellow iron staining. Luster: Vitreous to dull. Structure: Phaneritic (coarse-grained) crystalline texture. Cleavage: None (though minerals within it like mica have perfect cleavage).

Formation & Geological History

Formed from the slow crystallization of magma below Earth's surface (intrusive). Most granites date from the Precambrian or Paleozoic eras and form deep within the continental crust.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments due to its durability and resistance to weathering.

Geological Facts

Granite makes up a large portion of the Earth's continental crust. It is one of the hardest substances in the world, second only to diamonds. The name comes from the Latin 'granum', meaning a grain, in reference to its coarse-grained structure.

Field Identification & Locations

Identify by its interlocking 'mosaic' of visible crystals (quartz, feldspar, and mica). It is found globally in mountain ranges and continental shields. For collectors, look for uniform crystal size and lack of layering (which would indicate gneiss).

Identified on: 4/17/2026

Mode: Standard