igneous or metamorphic

Rounded river cobble, likely weathered volcanic or metamorphic rock

Indeterminate from photograph; possible basaltic-andesite, rhyolite, or quartz-rich metamorphic lithology

AI-generated identification · may be incorrect

Smooth, water-worn, fine-grained pebble with muted pink-tan and gray-green coloration, dull to faintly earthy luster, and no visible crystals or cleavage. Estimated Mohs hardness 5–7; specific gravity cannot be determined visually.

Identified August 26, 2026More igneous or metamorphic →

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At a glance

Common name: Rounded river cobble, likely weathered volcanic or metamorphic rock
Scientific name: Indeterminate from photograph; possible basaltic-andesite, rhyolite, or quartz-rich metamorphic lithology
Category: igneous or metamorphic
Identified: August 26, 2026
Method: Standard

AI Estimated Value

Typically $0–$10 as an ordinary cobble; perhaps $10–$30 if locally significant, unusually colored, or sold as a polished/collectible specimen.

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

Formation & geological history

Likely formed as a coherent bedrock fragment, then rounded by prolonged stream or beach abrasion; its precise geological age and parent rock are unknown without locality and testing.

Uses & applications

Usually collected as a natural specimen, landscaping stone, or craft material; it has little industrial or jewelry value unless laboratory examination reveals an attractive or unusual lithology.

Geological facts

The rounded shape indicates transport and abrasion rather than its original formation. A streak test, hardness test, acid test, and fresh broken surface would substantially improve identification.

Field identification & locations

Commonly found in riverbeds, beaches, and glacial deposits. Inspect a fresh surface for quartz grains, feldspar, vesicles, layering, or sparkly mica; avoid destructive tests if it is a valued specimen.