sedimentary

River Rock (Mossy)

Stream-rounded Clast (likely Siltstone or Sandstone with bryophytes)

AI-generated identification · may be incorrect

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

Identified June 15, 2026More sedimentary →

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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.