igneous
Granite River Pebbles
Granite (Phaneritic Quartz-Feldspar Plutonic Rock)
Hardness: 6-7 on Mohs scale; Color: Pink, grey, and white mottled with black; Luster: Dull (weathered) to vitreous (minerals); Structure: Coarse-grained crystalline; Cleavage: None (fractures); SG: 2.6-2.7
- Hardness
- 6-7 on Mohs scale
- Color
- Pink, grey, and white mottled with black
- Luster
- Dull (weathered) to vitreous (minerals)
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Pink, grey, and white mottled with black; Luster: Dull (weathered) to vitreous (minerals); Structure: Coarse-grained crystalline; Cleavage: None (fractures); SG: 2.6-2.7
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonism) during the Precambrian or Paleozoic eras. These specific specimens have been rounded by fluvial erosion in a river or glacial environment.
Uses & applications
Used primarily for landscaping, decorative garden stones, construction aggregate, and as educational specimens for geology students.
Geological facts
Granite is the primary component of the Earth's continental crust. These pebbles contain significant amounts of orthoclase feldspar (pink) and quartz (translucent white/grey).
Field identification & locations
Identify by the 'salt and pepper' appearance of interlocking crystals. Common in riverbeds and glacial moraines globally, particularly in areas like the Great Lakes region or mountain runoff streams.
