igneous
Granite
Granite (Phaneritic Igneous Rock; primarily Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 on Mohs scale; Color: typically mottled grey, white, pink, or tan; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- typically mottled grey, white, pink, or tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: typically mottled grey, white, pink, or tan; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow cooling and crystallization of magma deep beneath the Earth's surface (plutonic). It can range from Precambrian to Cenozoic ages and is the primary component of continental crust.
Uses & applications
Extensively used in construction as dimension stone for countertops, flooring, and cladding. Also used in infrastructure as crushed stone, and occasionally polished for decorative items.
Geological facts
Granite makes up the core of most continental mountain ranges. The famous faces on Mount Rushmore are carved into a massive granite batholith in South Dakota.
Field identification & locations
Identified in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz and feldspar. Found globally in continental shield areas and mountain ranges like the Sierra Nevada or the Rockies.
