igneous
Granite
Granite (Phaneritic igneous rock)
Hardness: 6-7 on Mohs scale; Color: Pink, orange, gray, and black mottled pattern; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: None (fractures); Specific Gravity: 2.63 - 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, orange, gray, and black mottled pattern
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, orange, gray, and black mottled pattern; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: None (fractures); Specific Gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen appears water-worn, likely found in a riverbed or glacial deposit. Can range from Precambrian to Cenozoic in age.
Uses & applications
Used extensively in construction for countertops, floor tiles, and monuments. Also used as crushed stone for road base and aggregate.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. Commonly found in mountainous regions or areas with exposed continental shields.
