Granite

Physical Properties

Hardness: 6-7 on Mohs scale. Color: Mottled pink, white, gray, and black. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained) featuring potassium feldspar, quartz, and mica. Specific Gravity: 2.63 - 2.75.

Formation & Geological History

Formed through the slow crystallization of magma below Earth's surface (intrusive). Most granites date back to the Precambrian or Paleozoic eras, forming in the roots of mountain ranges over millions of years.

Uses & Applications

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

Geological Facts

Granite makes up much of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable natural stones, resistant to weathering and acid.

Field Identification & Locations

Identify by its 'salt and pepper' or mottled appearance with visible interlocking crystals of different colors. It is commonly found in mountainous regions or areas where ancient bedrock has been exposed by erosion. Look for the presence of translucent quartz and salmon-pink feldspar.

Identified on: 4/29/2026

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