Mixed (Sedimentary, Igneous, and Metamorphic)

River Rocks (Polished River Pebbles)

Stream-rounded clastic sediments

Hardness: Variable (mostly 6-7 on Mohs scale), Color: Multicolored (tans, greys, blacks, greens), Luster: Dull to waxy when wet, Crystal structure: Varies by rock type, Specific gravity: 2.5-2.8

Identified June 8, 2026More mixed (sedimentary, igneous, and metamorphic) →

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Physical properties

Hardness: Variable (mostly 6-7 on Mohs scale), Color: Multicolored (tans, greys, blacks, greens), Luster: Dull to waxy when wet, Crystal structure: Varies by rock type, Specific gravity: 2.5-2.8

Formation & geological history

Formed through mechanical erosion and abrasion in high-energy fluvial (river) environments over thousands of years; these specimens represent a mix of geological ages from various parent formations.

Uses & applications

Landscaping, decorative garden mulch, aquarium substrate, construction aggregate, and occasionally used in mosaics or as base materials for paths.

Geological facts

The smooth, rounded shape is the result of 'saltation'—the process where rocks bounce along riverbeds, grinding against each other until sharp edges are worn away. The green specimen is likely serpentinite or greenstone.

Field identification & locations

Identify in the field by their smooth, rounded edges and lack of sharp fractures; commonly found in riverbeds, glacial till, and coastal beaches. Collectors look for unique patterns or rare minerals within the mix.

Other mixed (sedimentary, igneous, and metamorphic) specimens

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Granite or Granitic Gneiss

Granitoid / Gneiss

Igneous / Metamorphic

General Gravel (River Rock/River Stones)

Mixed Lithic Sediments (Conglomerate Clasts)

sedimentary

Venetian Gold Granite

Phaneritic Felsic Igneous Rock (Granite)

igneous

Arkosic Sandstone (or Conglomeritic Sandstone fragment)

Arkose (rich in feldspar)

sedimentary

Aventurine (Green Quartz)

Silicon Dioxide (SiO2) with inclusions of Fuchsite (Mica)

mineral

Assorted Decorative Tumbled Stones (Quartz, Sodalite, Aventurine, Calcite)

Mixed Silicates and Carbonates (SiO2, Na8(Al6Si6O24)Cl2, CaCO3)

mineral