igneous
Granite Pebble
Intrusive Igneous Rock (Granite)
Hardness: 6-7 on Mohs scale; Color: Speckled gray, pink, white, and dark green/black; Luster: Vitreous to dull; Texture: Phaneritic (medium to coarse-grained interlocked crystals); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled gray, pink, white, and dark green/black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Speckled gray, pink, white, and dark green/black; Luster: Vitreous to dull; Texture: Phaneritic (medium to coarse-grained interlocked crystals); Specific Gravity: 2.63-2.75
Formation & geological history
Formed by the slow crystallization of felsic magma deep beneath Earth's surface (plutonic environment). The rounded shape indicates erosion and weathering from water or glacial action.
Uses & applications
Commonly used in construction, road aggregate, landscape design, counter tops, and as educational river pebble specimens.
Geological facts
Granite makes up much of Earth's continental crust. The distinct speckled salt-and-pepper appearance comes from a mix of quartz, feldspar, biotite mica, and amphibole minerals.
Field identification & locations
Identified by visible interlocking mineral grains of light-colored quartz and feldspar mixed with dark ferromagnesian minerals, along with a rounded, water-worn exterior. Commonly found in riverbeds, glacial deposits, and beaches.
