igneous
Granite
Phaneritic Felsic Igneous Rock (composed主に of SiO2, Al2O3, K2O, Na2O)
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (gray, white, black). Luster: Dull to vitreous. Crystal structure: Phaneritic (visible coarse-grained crystals), roughly 2.65-2.75 specific gravity.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (gray, white, black)
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (gray, white, black). Luster: Dull to vitreous. Crystal structure: Phaneritic (visible coarse-grained crystals), roughly 2.65-2.75 specific gravity.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (plutonic). Found in continental crust, often dating back hundreds of millions to billions of years in orogenic belts.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone/aggregate for roads.
Geological facts
Granite makes up a large portion of the Earth's continental crust and is one of the hardest natural stones. Mount Rushmore is carved into a massive granite batholith in the Black Hills.
Field identification & locations
Identify by its interlocking grains of quartz (glassy), feldspar (opaque white/pink), and mica (shiny black flakes). It is found worldwide in mountain ranges and Shields.
