igneous
Granite
Granite (composition of Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale; Color: Pinkish-tan with some dark speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (large, coarse-grained crystals); Cleavage: Indistinct; Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Pinkish-tan with some dark speckles
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pinkish-tan with some dark speckles; Luster: Vitreous to dull; Crystal structure: Phaneritic (large, coarse-grained crystals); Cleavage: Indistinct; Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). Most granites are associated with continental crust and can range from Precambrian to Cenozoic ages.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, and memorial monuments. Also used as crushed stone for road bases.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Because of its durability and hardness, it has been used in architecture since Ancient Egypt (e.g., the Red Pyramid).
Field identification & locations
Identify in the field by its speckled, interlocking crystalline texture where individual grains of pink feldspar and clear quartz are visible. Common in mountainous regions with exposed batholiths.
