igneous
Granite
Granite (Felsic Intrusive)
Hardness: 6-7 on Mohs scale. Color: Spotted pink, white, and black. Luster: Vitreous to dull. Structure: Phaneritic (coarse-grained crystals). Cleavage: Non-existent in the rock itself, though mineral components like mica have perfect cleavage. Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Spotted pink, white, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Spotted pink, white, and black. Luster: Vitreous to dull. Structure: Phaneritic (coarse-grained crystals). Cleavage: Non-existent in the rock itself, though mineral components like mica have perfect cleavage. Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (plutonic). Found in continental crust, often appearing in mountain ranges or cratons. Can be hundreds of millions to billions of years old.
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.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most resistant rocks used by humans throughout history.
Field identification & locations
Identify by its interlocking 'salt and pepper' appearance of quartz (clear/gray), feldspar (pink/white), and biotite or hornblende (black). It is found worldwide in mountainous regions. Collectors look for large crystals or unique coloration.
