igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (mottled grey, white, and black). Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained crystals visible to the naked eye). Specific gravity: 2.63-2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt-and-pepper (mottled grey, white, and black)
- Luster
- Dull to vitreous
Identified More igneous →
Explore Granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt-and-pepper (mottled grey, white, and black). Luster: Dull to vitreous. Crystal structure: Phaneritic (coarse-grained crystals visible to the naked eye). Specific gravity: 2.63-2.75.
Formation & geological history
Formed by the slow crystallization of magma below the Earth's surface (intrusive). Composed primarily of quartz, feldspar, and plagioclase with minor amounts of mica and amphibians. Can date from the Archean Eon to recent times.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments. Also used as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up a large portion 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 'mosaic' texture of visible crystals and the presence of clear/grey quartz grains alongside opaque white/pink feldspar. Commonly found in mountainous regions or glacial drift.
