igneous
Granite
Granite (Mainly Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 on Mohs scale. Color: Speckled white, grey, and black. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Cleavage: Varies by mineral component. Specific gravity: 2.63-2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled white, grey, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled white, grey, and black. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained). Cleavage: Varies by mineral component. Specific gravity: 2.63-2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is an intrusive rock typically formed in continental crusts over millions of years.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, monuments, and as aggregate for roads.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith in the Black Hills of South Dakota.
Field identification & locations
Identify in the field by its interlocking 'salt and pepper' crystalline texture where minerals are large enough to see with the naked eye. Found globally in mountainous regions and shield areas.
