igneous
Granite
Granite (Mainly Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 Mohs; Color: Salt and pepper/greyish-tan; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (fractures), though feldspar crystals within may exhibit cleavage.
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper/greyish-tan
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper/greyish-tan; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (fractures), though feldspar crystals within may exhibit cleavage.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). Usually associated with mountain-building events in the continental crust. Can date back billions of years depending on location.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is extremely durable and resistant to weathering, which is why it is used for prominent landmarks like Mount Rushmore.
Field identification & locations
Identify by its 'salt and pepper' appearance and visible interlocking crystals of different colors (clear/white quartz, pinkish/tan feldspar, dark mica). Common in mountain ranges and batholiths worldwide.
