Mixed (predominantly sedimentary and igneous)

River Rock (Glacial Cobbles)

Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)

AI-generated identification · may be incorrect

Hardness: 5-7 on Mohs scale; Color: Multi-colored (grey, tan, white, brown); Luster: Dull to earthy; Texture: Smooth, rounded, and water-worn; Structure: Granular or massive.

Hardness: 5-7 on Mohs scale
Color: Multi-colored (grey, tan, white, brown)
Luster: Dull to earthy

Identified March 8, 2026More mixed (predominantly sedimentary and igneous) →

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At a glance

Common name: River Rock (Glacial Cobbles)
Scientific name: Fluvial Alluvium (Mixed lithology including Quartzite, Basalt, and Granite)
Category: Mixed (predominantly sedimentary and igneous)
Identified: March 8, 2026
Method: Standard

AI Estimated Value

$0.05 - $0.50 per pound as bulk landscaping material; $1 - $10 for unique hand-selected specimens with interesting colors or patterns.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Hardness: 5-7 on Mohs scale; Color: Multi-colored (grey, tan, white, brown); Luster: Dull to earthy; Texture: Smooth, rounded, and water-worn; Structure: Granular or massive.

Formation & geological history

Formed through the weathering and erosion of pre-existing bedrock, transported by high-energy water environments like rivers or glaciers during the Pleistocene epoch. Continuous tumbling in water polishes the sharp edges into smooth ovals.

Uses & applications

Used extensively in landscaping, decorative ground cover, construction aggregate, drainage systems, and as architectural accents in gardens and ponds.

Geological facts

River rocks are geological 'time capsules' because a single handful can contain stones formed millions of years apart and from vastly different geographic regions, brought together by glacial movement or long-distance river transport.

Field identification & locations

Identify by their characteristic rounded, smooth surface and lack of sharp edges. Look for them in dry creek beds, riverbanks, and glacial moraines. For collectors, look for unique patterns or inclusions like quartz veining.