igneous
Granite
Phaneritic plutonic rock (approx. 20-60% quartz, 35-90% feldspar)
Hardness: 6-7 on Mohs scale; Color: Pink, reddish-brown, white, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: None (it fractures); Specific Gravity: 2.63 - 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, reddish-brown, white, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, reddish-brown, white, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: None (it fractures); Specific Gravity: 2.63 - 2.75
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface (intrusive). Geological ages vary widely from the Archean Eon to the Cenozoic, commonly found in continental crust and mountain ranges.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, and memorial monuments. It is also used as crushed stone for road base and aggregate in concrete.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Famous landmarks like Mount Rushmore and Yosemite's El Capitan are composed of granite. The pink color in this specimen is specifically due to potassium-rich orthoclase feldspar.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and large, interlocking mineral grains of quartz (clear/grey) and feldspar (pink/white). It can be found globally in cratons and mountain cores.
