sedimentary
River Pebbles (Mixed Lithology)
Conglomerate clasts (Silica-rich and Metamorphic assemblages)
Hardness: 6-7 (Mohs); Color: Grey, white, green, and banded; Luster: Dull to waxy; Texture: Smooth, water-worn, rounded; Specific Gravity: ~2.6-2.8
- Hardness
- 6-7 (Mohs)
- Color
- Grey, white, green, and banded
- Luster
- Dull to waxy
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Physical properties
Hardness: 6-7 (Mohs); Color: Grey, white, green, and banded; Luster: Dull to waxy; Texture: Smooth, water-worn, rounded; Specific Gravity: ~2.6-2.8
Formation & geological history
Formed through the mechanical weathering and transport of various parent rocks (magmatic and metamorphic) in high-energy fluvial environments like rivers or beaches. These specimens are likely Holocene to Pleistocene in transport age.
Uses & applications
Decorative landscaping, aquarium substrate, construction aggregate, and amateur rock collecting (lapidary tumbling).
Geological facts
The smooth, rounded shape is a result of 'attrition,' where rocks collide with each other in water currents, gradually wearing down sharp edges over hundreds of miles of travel.
Field identification & locations
Identify by their rounded, smooth texture and lack of sharp edges. They are found in riverbeds, glacial till, and coastal shorelines globally. These specific pieces show quartz and possible schist/gneiss origins.
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