igneous
Granite
Granite
Hardness: 6-7 on Mohs scale; Color: Pink, light gray, with black specks; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained) with visible crystals of quartz, feldspar, and mica; Cleavage: None (the mineral components have cleavage, but the rock itself fractures).
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, light gray, with black specks
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, light gray, with black specks; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained) with visible crystals of quartz, feldspar, and mica; Cleavage: None (the mineral components have cleavage, but the rock itself fractures).
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). Most granite dates back to the Precambrian or Paleozoic eras. It forms in continental crust at subduction zones or mountainbuilding events.
Uses & applications
Extensively used in construction for countertops, floor tiles, paving stone, monuments, 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 massive granite batholith in the Black Hills of South Dakota.
Field identification & locations
Identify by its interlocking 'salt and pepper' appearance and hardness. It is commonly found in mountain ranges and ancient continental shields. Collectors look for unique mineral inclusions like large tourmaline or garnet crystals within the matrix.
