igneous
Granite
Felsic intrusive igneous rock
Hardness: 6-7 (Mohs). Color: White, gray, and tan with black specs. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained), crystalline. Cleavage: Indistinct. Specific gravity: 2.63 to 2.75.
- Hardness
- 6-7 (Mohs)
- Color
- White, gray, and tan with black specs
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs). Color: White, gray, and tan with black specs. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained), crystalline. Cleavage: Indistinct. Specific gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. Composed primarily of quartz, feldspar, and plagioclase with minor amounts of mica and amphiboles. Often hundreds of millions of years old.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, curbing, monuments, and as crushed stone for road base.
Geological facts
Granite is the most common igneous rock found at Earth's surface and makes up a large part of the continental crust. It is extremely durable and resistant to weathering.
Field identification & locations
Identified by its visible interlocking crystals of different colors. It is found in mountain ranges and continental shields. Collectors look for unique mineral inclusions or large phenocrysts (porphyritic texture).
