Granite

Physical Properties

Hardness (Mohs scale): 6 to 7. Color: Grey, pink, white, or red with dark specks. Luster: Dull to pearly. Crystal structure: Phaneritic (coarse-grained). Cleavage: Indistinct. Specific gravity: 2.63 to 2.75.

Formation & Geological History

Formed from the slow cooling and solidification of magma deep within the Earth's crust (intrusive). They can be billions of years old, often found in the core of mountain ranges.

Uses & Applications

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

Geological Facts

Granite is the most common igneous rock found on Earth's continents. It contains minerals like quartz, feldspar, and mica. The famous faces on Mount Rushmore are carved into granite.

Field Identification & Locations

Identify by its coarse-grained texture and interlocking crystals of quartz and feldspar. Found globally in continental crust areas like the Sierra Nevada or the Scottish Highlands. Collectors look for unique mineral inclusions.

Identified on: 4/15/2026

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