igneous
Granite
Granite (Mainly Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 on Mohs scale; Color: Light gray to tan with salt-and-pepper flecks; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Light gray to tan with salt-and-pepper flecks
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Light gray to tan with salt-and-pepper flecks; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained); Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is a plutonic rock found in continental crust, often dating from the Precambrian to Cenozoic eras.
Uses & applications
Used extensively in construction (curbing, pavers), interior design (countertops, floor tiles), and as dimension stone for monuments and public buildings.
Geological facts
Granite makes up a large part of the Earth's continental crust. Mount Rushmore is carved into a granite batholith in the Black Hills of South Dakota.
Field identification & locations
Identify in the field by its interlocking visible crystals of light-colored minerals (quartz/feldspar) and dark minerals (biotite/amphibole). It is found globally in mountain ranges and eroded shield areas.
