igneous
Granite
Granite (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 Mohs; Color: White, gray, or pinkish with black specks; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained, visible crystals); Cleavage: Indistinct; Specific Gravity: 2.63 to 2.75
- Hardness
- 6-7 Mohs
- Color
- White, gray, or pinkish with black specks
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-7 Mohs; Color: White, gray, or pinkish with black specks; Luster: Vitreous to pearly; Crystal structure: Phaneritic (coarse-grained, visible crystals); Cleavage: Indistinct; Specific Gravity: 2.63 to 2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). It is found in the continental crust and often dates back hundreds of millions to billions of years.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, monuments, and as crushed stone for road base.
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 by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. Found globally in mountainous regions or areas where ancient crust is exposed.
