igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6-7 on Mohs scale. Color: Spotted or speckled mix of tan, gray, and black. Luster: Vitreous to dull. Crystal Structure: Phaneritic (coarse-grained). Cleavage: Varies by mineral content. Specific Gravity: 2.65 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Spotted or speckled mix of tan, gray, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Spotted or speckled mix of tan, gray, and black. Luster: Vitreous to dull. Crystal Structure: Phaneritic (coarse-grained). Cleavage: Varies by mineral content. Specific Gravity: 2.65 to 2.75.
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (intrusive). They can be hundreds of millions to billions of years old, often found in the continental crust.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments because of its durability and aesthetic appeal.
Geological facts
Granite makes up a large part of the Earth's continental crust. It is one of the hardest substances in the world, second only to diamonds. Famous landmarks like Mount Rushmore are carved from granite.
Field identification & locations
Identify in the field by its interlocking coarse grains of quartz, feldspar, and mica. It is ubiquitous in mountainous regions and shield areas like the Canadian Shield or the Appalachians.
