igneous
Granite
Granite (Mainly Quartz, Feldspar, and Mica)
Hardness: 6-7 on Mohs scale. Color: White, pink, or gray with mottled dark spots. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, visible crystals). Cleavage: Varies by mineral inside (Feldspar has good cleavage, Quartz has none). Specific Gravity: 2.63 to 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- White, pink, or gray with mottled dark spots
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale. Color: White, pink, or gray with mottled dark spots. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, visible crystals). Cleavage: Varies by mineral inside (Feldspar has good cleavage, Quartz has none). Specific Gravity: 2.63 to 2.75.
Formation & geological history
Formed through the slow crystallization of magma below the Earth's surface (intrusive). Most common in continental crust, with some formations dating back billions of years to the Precambrian era.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stones, and monuments. Also used as crushed stone for road base and railroad ballast.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Famous natural landmarks like Mount Rushmore and Yosemite's Half Dome are composed almost entirely of granite. It is one of the hardest and most durable common stones.
Field identification & locations
Identify in the field by its 'salt and pepper' look and crystalline texture where individual grains of quartz and feldspar are visible to the naked eye. Found globally in mountain ranges and shields. Collectors look for large crystals or unique coloration.
