igneous
Granite
Phaneritic Felsic Plutonic Rock
Hardness: 6-7 (Mohs scale); Color: Pinkish-brown with black and white speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Composition: Quartz, Potassium Feldspar, and Biotite mica; Specific Gravity: 2.63-2.75
- Hardness
- 6-7 (Mohs scale)
- Color
- Pinkish-brown with black and white speckles
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Pinkish-brown with black and white speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (coarse-grained); Composition: Quartz, Potassium Feldspar, and Biotite mica; Specific Gravity: 2.63-2.75
Formation & geological history
Formed by the slow crystallization of magma below the Earth's surface (intrusive). The pink color comes from potassium feldspar, white from quartz, and black from biotite or hornblende.
Uses & applications
Widely used in construction, countertops, monuments, curbing, and as decorative crushed stone for landscaping.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in the Black Hills of South Dakota.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking mineral crystals. It is extremely common in mountainous regions and glacial till.
