igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6-7 Mohs; Color: Pink, white, gray, or black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Imperfect; Specific gravity: 2.63 - 2.75
- Hardness
- 6-7 Mohs
- Color
- Pink, white, gray, or black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Pink, white, gray, or black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Imperfect; Specific gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface (intrusive). Geological age spans from the Archean Eon to the Cenozoic, found globally in continental crust.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, and monuments. Also value as a decorative building stone and in crushed form as road base.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Famous specimens include the massive monoliths of Yosemite National Park (El Capitan). It is extremely resistant to weathering and acid rain.
Field identification & locations
Identify in the field by its interlocking, visible crystals of quartz (clear/gray), feldspar (pink/white), and mica (black/shiny). Common in mountain ranges and eroded shields. Look for a 'salt and pepper' appearance.
