igneous
Granite
Granite (Phaneritic igneous rock consisting of Quartz, Feldspar, and Mica)
Hardness: 6-7 Mohs; Color: Salt and pepper appearance (grey, white, pink, black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper appearance (grey, white, pink, black)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper appearance (grey, white, pink, black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75
Formation & geological history
Forms from the slow crystallization of magma below Earth's surface in continental crust plutons. It can date back to billions of years (Archean Eon) to more recent eras.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, monuments, and as a dimension stone for architectural cladding.
Geological facts
Granite makes up the majority of the Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.
Field identification & locations
Identify by its interlocking 'salt and pepper' grains of white/clear quartz, opaque pink or white feldspar, and black biotite or hornblende. Commonly found in mountain ranges and eroded crystalline shields.
