igneous
Granite
Phaneritic intrusive igneous rock (consisting mainly of Quartz, Alkali Feldspar, and Plagioclase)
Hardness: 6-7 on Mohs scale; Color: Pink, white, and gray speckled; Luster: Vitrous to dull; Crystal structure: Phaneritic (coarse-grained crystals visible to the naked eye); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, white, and gray speckled
- Luster
- Vitrous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, white, and gray speckled; Luster: Vitrous to dull; Crystal structure: Phaneritic (coarse-grained crystals visible to the naked eye); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface. This specimen likely originates from a deep-seated pluton that was subsequently exposed by erosion. Ages can range from Precambrian to Cenozoic depending on the tectonic setting.
Uses & applications
Used extensively in construction for countertops, floor tiles, paving stones, curbing, and monuments. It is also a popular material for rock climbing and as crushed stone for road base.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Mount Rushmore is carved into a granite batholith. It is one of the hardest and most durable natural stones used by humans since ancient times.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz (glassy) and feldspar (opaque pink/white). It is common in mountainous regions and continental shields like the Canadian Shield.
