Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Salt and pepper/white-grey with black flecks; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Specific gravity: 2.63 - 2.75.

Formation & Geological History

Formed through the slow crystallization of magma below Earth's surface. This specific specimen appears to be a river-worn cobble, rounded by water erosion. It can be from any geological age, commonly found in continental crust batholiths.

Uses & Applications

Used extensively in construction for countertops, floor tiles, paving stone, monuments, and as crushed stone for road base and concrete aggregate.

Geological Facts

Granite is the most common rock found in the Earth's continental crust. It is incredibly durable and because it is an intrusive rock, it has large crystals that took thousands of years to cool.

Field Identification & Locations

Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. Found globally in mountainous regions or riverbeds. For collectors, look for smoothness and distinct mineral grains.

Identified on: 4/25/2026

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