igneous
Granite
Phaneritic Felsic Igneous Rock (Main minerals: SiO2, KAlSi3O8, NaAlSi3O8)
Hardness: 6-7 Mohs; Color: Salt and pepper/mottled grey, tan, and white; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Specific gravity: 2.63 - 2.75.
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper/mottled grey, tan, and white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper/mottled grey, tan, and white; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Specific gravity: 2.63 - 2.75.
Formation & geological history
Formed by the slow crystallization of magma below Earth's surface (intrusive). Most granite dates to various eras throughout the Precambrian, Paleozoic, and Mesozoic, forming in continental crustal environments.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments due to its durability and aesthetic appeal.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith, and the rock is known for being extremely resistant to weathering.
Field identification & locations
Identify in the field by its light color and interlocking, multi-colored mineral grains (quartz, feldspar, and mica) that are large enough to see with the naked eye. Found globally in mountainous regions and shield areas.
