igneous
Granite
Phaneritic plutonic igneous rock (typically 20% to 60% quartz by volume)
Hardness: 6-7 (Mohs scale); Color: Pink, orange, and white grains with black speckles; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Specific Gravity: 2.63 to 2.75
- Hardness
- 6-7 (Mohs scale)
- Color
- Pink, orange, and white grains with black speckles
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Pink, orange, and white grains with black speckles; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Specific Gravity: 2.63 to 2.75
Formation & geological history
Formed from the slow crystallization of silica-rich magma deep beneath the Earth's surface (plutonic formation). This specimen appears to be water-worn, likely from a riverbed or glacial deposit.
Uses & applications
Widely used as a construction material, dimension stone for countertops and monuments, and crushed stone for road base. Specimens like this are common for educational collections.
Geological facts
Granite is the most common igneous rock found on Earth's continents and makes up the bulk of the continental crust. The pink color in this specimen is specifically due to potassium-rich alkali feldspar.
Field identification & locations
Identify in the field by the visible 'salt and pepper' interlocking crystals of quartz, feldspar, and biotite mica. Common in mountain ranges and glacial till across North America and Europe.
