igneous
Granite
Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 (Mohs); Color: Mottled pink, white, and grey; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained visible crystals); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 (Mohs)
- Color
- Mottled pink, white, and grey
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs); Color: Mottled pink, white, and grey; Luster: Dull to vitreous; Crystal Structure: Phaneritic (coarse-grained visible crystals); Specific Gravity: 2.63-2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface (intrusive). The visible grains indicate a slow cooling process over thousands of years, typically found in continental crust and mountain ranges.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and memorial monuments due to its durability and resistance to weathering.
Geological facts
Granite is the most common intrusive igneous rock in Earth's continental crust. Mount Rushmore is carved into a massive granite batholith in South Dakota.
Field identification & locations
Identify by looking for a 'salt and pepper' or mottled appearance with distinct interlocking crystals of quartz (clear/grey) and feldspar (pink/white). It is everywhere in ancient crystalline shield areas like Canada or the Appalachian mountains.
