igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Mottled grey, white, and pinkish-brown with visible crystals. Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained). Cleavage: Varies by internal mineral; specific gravity is approx 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled grey, white, and pinkish-brown with visible crystals
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Mottled grey, white, and pinkish-brown with visible crystals. Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained). Cleavage: Varies by internal mineral; specific gravity is approx 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). The coarseness indicates it spent a long time cooling in the crust. Found in continental crust ranging from Precambrian to Cenozoic eras.
Uses & applications
Major use in construction for countertops, floor tiles, paving stones, curbing, and monuments. Also used as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up the core of most mountain ranges. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable common stones, making it the preferred material for kitchen surfaces.
Field identification & locations
Identify in the field by its 'salt and pepper' look and interlocked visible crystals of quartz, feldspar, and mica. Commonly found in outcroppings in mountainous regions or glacial till. Does not fizz with acid.
