igneous
Granite
Granite (Phaneritic Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: White, gray, and black mottled appearance. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral (perfect in mica, poor in quartz). Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- White, gray, and black mottled appearance
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: White, gray, and black mottled appearance. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral (perfect in mica, poor in quartz). Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). Composed mainly of quartz, feldspar, and mica. Geological age varies widely from Precambrian to Cenozoic.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, curbing, and monuments. Also popular as a collector's specimen for demonstrating igneous textures.
Geological facts
Granite makes up a large portion 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 available.
Field identification & locations
Identify in the field by its coarse 'salt and pepper' appearance and hardness (cannot be scratched by a steel knife). Commonly found in mountain ranges and continental shields globally.
