igneous
Granite
Intrusive igneous rock (SiO2 range 65-75%)
Hardness: 6-7 Mohs; Color: Mottled grey, white, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: Uneven fracture; Specific Gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Mottled grey, white, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Mottled grey, white, and black; Luster: Dull to vitreous; Crystal Structure: Phaneritic (visible crystals); Cleavage: Uneven fracture; Specific Gravity: 2.63-2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface in batholiths and plutons. It is a major component of continental crust and can date back billions of years.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monument building because of its durability and aesthetic appeal.
Geological facts
Granite is the most common igneous rock found at Earth's surface. Mount Rushmore is carved into a massive granite batholith in South Dakota, USA.
Field identification & locations
Identify by its interlocking 'salt and pepper' appearance of quartz (clear/white), feldspar (white/pink), and mica (black). It is found in mountain ranges and ancient shields globally.
