igneous
Granite
Granite (Phaneritic Igneous Rock)
Hardness: 6-7 on Mohs scale; Color: Speckled gray, black, and white; Luster: Variable (glassy quartz, pearly feldspar); Crystal structure: Phaneritic (coarse-grained), crystalline; Specific gravity: 2.63 - 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled gray, black, and white
- Luster
- Variable (glassy quartz, pearly feldspar)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Speckled gray, black, and white; Luster: Variable (glassy quartz, pearly feldspar); Crystal structure: Phaneritic (coarse-grained), crystalline; Specific gravity: 2.63 - 2.75.
Formation & geological history
Formed by the slow crystallization of magma below Earth's surface. It is a coarse-grained intrusive rock. Common in continental crust and mountain ranges, often dating back hundreds of millions of years.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest natural stones available.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. It is common in rocky outcrops and glacial deposits.
