igneous
Granite
Phaneritic Igneous Rock (composed mostly of Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale; Color: Pink, white, gray, and black mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained/visible crystals); Specific Gravity: 2.65-2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, white, gray, and black mottled
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, white, gray, and black mottled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained/visible crystals); Specific Gravity: 2.65-2.75
Formation & geological history
Formed from the slow subterranean cooling of silica-rich magma (plutonic). Found in continental crust, often dating back hundreds of millions or billions of years.
Uses & applications
Widely used in construction, countertops, monuments, curbing, and as crushed stone for road bases.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith.
Field identification & locations
Identify by its interlocking 'salt and pepper' appearance of different colored minerals; it is extremely hard and cannot be scratched by a steel nail. Common in mountainous regions or glacial deposits.
