igneous
Granite
Phaneritic plutonic rock (Quartz, Feldspar, Mica)
Hardness: 6-7 Mohs; Color: Pink, grey, white, and black speckled; Luster: Vitreous/Dull; Crystal Structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 - 2.75
- Hardness
- 6-7 Mohs
- Color
- Pink, grey, white, and black speckled
- Luster
- Vitreous/Dull
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Physical properties
Hardness: 6-7 Mohs; Color: Pink, grey, white, and black speckled; Luster: Vitreous/Dull; Crystal Structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 - 2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is a plutonic rock that cools over millions of years, allowing large crystals to grow. Most granites date from the Precambrian to Cenozoic eras.
Uses & applications
Widely used in construction for countertops, floor tiles, paving stones, curbing, and monuments. Also used as crushed stone/aggregate for road base and concrete.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest natural stones, which is why it has been used in architecture since ancient Egypt.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz (clear/grey) and feldspar (pink/white). Found globally in mountain ranges and continental shields. Collectors look for unique mineral inclusions like tourmaline or large feldspar phenocrysts.
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