igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper look with pink, white, gray, and black. Luster: Vitreous to dull. Structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral, generally irregular fracture.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled salt-and-pepper look with pink, white, gray, and black. Luster: Vitreous to dull. Structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral, generally irregular fracture.
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (intrusive). Most continental granite dates from the Precambrian to Cenozoic eras, typically forming in continental crust above subduction zones.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and monuments due to its durability and resistance to weathering. Also used 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 South Dakota. Because it contains trace amounts of uranium, some granite can emit small amounts of radon gas.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz (clear/gray), feldspar (white/pink), and mica (black/shiny). Found globally in mountain ranges and continental shields.
