igneous
Red Granite
Potassium-feldspar rich Granite
Hardness: 6-7 (Mohs); Color: Pink to deep red with black and white mottling; Luster: Vitreous to dull; Structure: Phaneritic (coarse-grained crystals); Composition: Orthoclase feldspar, quartz, and hornblende/biotite mica.
- Hardness
- 6-7 (Mohs)
- Color
- Pink to deep red with black and white mottling
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 (Mohs); Color: Pink to deep red with black and white mottling; Luster: Vitreous to dull; Structure: Phaneritic (coarse-grained crystals); Composition: Orthoclase feldspar, quartz, and hornblende/biotite mica.
Formation & geological history
Formed through the slow cooling and crystallization of molten magma deep beneath the Earth's surface (intrusive igneous). It can range from hundreds of millions to billions of years old.
Uses & applications
Extensively used in construction for countertops, floor tiles, monuments, and as crushed stone for road sub-base. Red varieties are particularly prized for decorative tombstone and building facades.
Geological facts
The red color is caused by an abundance of pinkish-red potassium feldspar (orthoclase). Granite makes up a large portion of the Earth's continental crust but is absent from the ocean floor.
Field identification & locations
Identify by its interlocking 'salt and pepper' crystalline texture and extreme hardness (cannot be scratched by a steel knife). Commonly found in continental mountain ranges and shield regions like the Canadian Shield.
