igneous
Granite
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (white, gray, black); Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained visible crystals); Cleavage: No overall cleavage (though individual feldspar grains exhibit it); Specific Gravity: 2.63 to 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (white, gray, black)
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper (white, gray, black); Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained visible crystals); Cleavage: No overall cleavage (though individual feldspar grains exhibit it); Specific Gravity: 2.63 to 2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (intrusive). Geological age spans from the Archean Eon to the Cenozoic, commonly found in continental crust and mountain ranges.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and monuments due to its durability and aesthetic appeal. Also used as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith, and it is one of the hardest natural substances used in commercial construction.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and large, interlocking mineral grains. Look for translucent quartz, opaque white/pink feldspar, and dark flakes of mica or hornblende. Commonly found in batholiths and mountain cores.
