igneous
Granite
Granite (phaneritic intrusive igneous rock consisting of quartz, feldspar, and mica)
Hardness: 6-7 on Mohs scale. Color: Gray, salt-and-pepper, or pinkish tones. Luster: Vitreous to dull. Crystal Structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral constituent; specific gravity: 2.63 - 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Gray, salt-and-pepper, or pinkish tones
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Gray, salt-and-pepper, or pinkish tones. Luster: Vitreous to dull. Crystal Structure: Phaneritic (coarse-grained visible crystals). Cleavage: Varies by mineral constituent; specific gravity: 2.63 - 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. It is a plutonic rock that forms over millions of years, often dating back to the Precambrian era through the Phanerozoic.
Uses & applications
Widely used in construction, countertops, monuments, paving stones, and as aggregate. It is also a popular specimen for educational geology kits.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Iconic natural landmarks like Yosemite's Half Dome and Mount Rushmore are made of granite.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz (clear/gray) and feldspar (white/pink). Commonly found in mountain ranges and continental shields. Collectors look for unique color variations or large phenocrysts.
