
igneous
Granite
Granite
Hardness: 6-7 on Mohs scale; Color: Variable, commonly white, pink, gray, or black, depending on mineral proportions. Often speckled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained) texture, displaying interlocking crystals; Cleavage: No true cleavage but exhibits fracture;…
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Variable, commonly white, pink, gray, or black, depending on mineral proportions. Often speckled; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained) texture, displaying interlocking crystals; Cleavage: No true cleavage but exhibits fracture; Specific gravity: 2.6-2.7 g/cm³
Formation & geological history
Formed from the slow crystallization of magma below the Earth's surface. This intrusive igneous rock solidifies deep within the crust. It is typically found in continental crust and forms the cores of mountain ranges, often exposed after uplift and erosion of overlying rocks. Geological age can range from Precambrian to Cenozoic.
Uses & applications
Widely used as building material for countertops, floor tiles, paving stones, and veneers due to its durability and aesthetic appeal. Also used in monuments, sculptures, and as crushed stone for road construction.
Geological facts
Granite is one of the most abundant intrusive igneous rocks in the Earth's continental crust. The term 'granite' is often used broadly to include a variety of coarse-grained igneous rocks. The famous Mount Rushmore National Memorial is carved into a granite batholith.
Field identification & locations
In the field, granite can be identified by its coarse-grained texture and the presence of visible, interlocking crystals of quartz (glassy, gray), feldspar (white, pink, or off-white, blocky), and dark minerals like biotite (black flakes) or hornblende (dark elongated crystals). It is commonly found in large continental landmasses, mountain belts, and shield areas worldwide. Tips for collectors include looking for freshly broken surfaces to better observe crystal characteristics and color variations.