igneous
Granite River Pebble
Granite (Phaneritic igneous rock)
Hardness: 6-7 (Mohs scale); Color: Pinkish-red, white, and grey mottled; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (individual minerals have cleavage); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 (Mohs scale)
- Color
- Pinkish-red, white, and grey mottled
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Pinkish-red, white, and grey mottled; Luster: Dull to vitreous; Structure: Phaneritic (coarse-grained) crystalline; Cleavage: None (individual minerals have cleavage); Specific Gravity: 2.63-2.75
Formation & geological history
Formed by the slow cooling of silica-rich magma deep underground. This specific specimen has been weathered and rounded by water transport in a river or coastal environment.
Uses & applications
Large-scale construction, architectural facades, countertops, road base, and as decorative river stones in landscaping.
Geological facts
Granite is the primary component of the Earth's continental crust. The pink hue in this specimen is caused by the presence of potassium feldspar (orthoclase).
Field identification & locations
Identify by its salt-and-pepper or mottled appearance and hardness (it will scratch glass). Commonly found in mountainous regions or as rounded pebbles in glacial till and riverbeds.
