sedimentary
River Stone (Chert/Basalt mix)
Microcrystalline Quartz (Chert) / Basalt
Hardness: 6-7 Mohs; Color: Dark grey to bluish-black; Luster: Dull to waxy; Structure: Cryptocrystalline/Aphanitic; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.9
- Hardness
- 6-7 Mohs
- Color
- Dark grey to bluish-black
- Luster
- Dull to waxy
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Physical properties
Hardness: 6-7 Mohs; Color: Dark grey to bluish-black; Luster: Dull to waxy; Structure: Cryptocrystalline/Aphanitic; Cleavage: None (conchoidal fracture); Specific Gravity: 2.5-2.9
Formation & geological history
Formed either through volcanic cooling (if basalt) or silica-rich chemical deposition in marine environments (if chert). This specimen has been rounded and smoothed by water erosion in a river or coastal environment.
Uses & applications
Landscaping, aquarium decor, historical tools (flintknapping), or common river gravel for construction.
Geological facts
Smooth river stones represent the geological cycle of erosion, where jagged mountain rocks are transported by water and polished over thousands of years into rounded shapes.
Field identification & locations
Identify by its smooth, water-worn texture and rounded edges. Common in stream beds, beaches, and glacial till. Highly durable and non-reactive.
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