sedimentary
River Rock (Mossy)
Stream-rounded Clast (likely Siltstone or Sandstone with bryophytes)
Hardness: Variable (3-7 Mohs); Color: Grey/Brown underlying green moss; Luster: Dull/Earthy; Crystal structure: Microcrystalline; Specific Gravity: ~2.5-2.7
- Hardness
- Variable (3-7 Mohs)
- Color
- Grey/Brown underlying green moss
- Luster
- Dull/Earthy
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Physical properties
Hardness: Variable (3-7 Mohs); Color: Grey/Brown underlying green moss; Luster: Dull/Earthy; Crystal structure: Microcrystalline; Specific Gravity: ~2.5-2.7
Formation & geological history
Formed through the erosion and transport of lithified sediment in a fluvial environment. The rounding is caused by abrasion against other rocks in moving water. Age varies by parent rock, often Paleozoic to Cenozoic.
Uses & applications
Landscaping, aquarium decoration, construction aggregate, and garden accents.
Geological facts
The green coating is likely moss or algae, which indicates the rock was recently in a moist, shaded environment. River rocks are naturally 'tumbled' by nature over hundreds or thousands of years.
Field identification & locations
Identified by its smooth, rounded edges and water-worn surface. Commonly found in riverbeds, streams, and glacial deposits. Collectors should look for unique shapes or mineral inclusions.
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