igneous
Granite
Granite (Felsic Plutonic Rock)
Hardness: 6-7 on Mohs scale. Color: Pink, gray, and black mottled pattern. Luster: Dull to vitreous. Structure: Phaneritic (coarse-grained) crystalline. Composition: Orthoclase feldspar (pink), Quartz (clear/white), and Biotite/Hornblende (black). Specific Gravity: 2.63-2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, gray, and black mottled pattern
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Pink, gray, and black mottled pattern. Luster: Dull to vitreous. Structure: Phaneritic (coarse-grained) crystalline. Composition: Orthoclase feldspar (pink), Quartz (clear/white), and Biotite/Hornblende (black). Specific Gravity: 2.63-2.75.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground in the Earth's crust (intrusive). They are primary components of continental crust and can be billions of years old.
Uses & applications
Widely used in construction, countertops, monuments, floor tiles, and as crushed stone for road bases. Also popular in landscaping.
Geological facts
Granite is the most common rock in Earth's continental crust. Mount Rushmore is carved into a massive granite batholith. Its resistance to acid and wear makes it one of the most durable building materials.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals. It is found in mountain ranges and eroded shield areas worldwide. Collectors look for unique mineral inclusions like tourmaline or garnets.
