igneous
Granite
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale; Color: Pink, white, gray, and black speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Dependent on mineral (poor in quartz, perfect in mica); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, white, gray, and black speckles
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, white, gray, and black speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Cleavage: Dependent on mineral (poor in quartz, perfect in mica); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). Commonly formed during orogenic (mountain-building) events across various geological eras, including the Precambrian and Paleozoic.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, curbing, and monuments. Also used as crushed stone for road base and railroad ballast.
Geological facts
Granite is the primary component of the Earth's continental crust. Mount Rushmore is carved into a granite batholith in the Black Hills of South Dakota. It is one of the hardest and most durable natural stones.
Field identification & locations
Identify by its interlocking granular texture where individual mineral crystals (quartz, feldspar, biotite) are visible to the naked eye. Found globally in mountainous regions and continental shields. Collectors look for unique inclusions or large crystals.
