igneous
Granite Pebble
Granite
Hardness: 6-7 (Mohs scale); Color: Mottled tan, orange, and black; Luster: Dull to vitreous; Texture: Phaneritic (coarse-grained crystals); Specific Gravity: 2.6-2.7
- Hardness
- 6-7 (Mohs scale)
- Color
- Mottled tan, orange, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Mottled tan, orange, and black; Luster: Dull to vitreous; Texture: Phaneritic (coarse-grained crystals); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the slow crystallization of magma below Earth's surface. This specific specimen has been smoothed by water erosion, likely in a river or coastal environment.
Uses & applications
Crushed stone for construction, architectural facade when in large slabs, and occasionally as decorative garden stones.
Geological facts
Granite is the primary rock type making up the Earth's continental crust. The black spots are likely biotite mica or hornblende, while the tan/orange is feldspar.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and hardness (it cannot be scratched by a steel knife). Common in mountain ranges and glacial deposits.
