sedimentary or metamorphic

Rounded river pebble, likely quartz-rich sandstone or quartzite

Indeterminate; probable quartz (SiO₂) with feldspar, iron-oxide staining, and minor lithic grains

AI-generated identification · may be incorrect

Smooth, water-rounded cobble with tan-gray to brown color, earthy-to-dull luster, and fine granular texture; likely Mohs 6–7 if quartz-rich, with no obvious cleavage. Exact identification requires a fresh surface, acid test, and hardness testing.

Identified August 29, 2026More sedimentary or metamorphic →

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At a glance

Common name: Rounded river pebble, likely quartz-rich sandstone or quartzite
Scientific name: Indeterminate; probable quartz (SiO₂) with feldspar, iron-oxide staining, and minor lithic grains
Category: sedimentary or metamorphic
Identified: August 29, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 as a common collected pebble; $10–$30 if unusually attractive, locality-labeled, or confirmed as distinctive quartzite.

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

Formed as a sedimentary sandstone and possibly weakly metamorphosed into quartzite, then rounded by abrasion in a river, beach, or glacial deposit. Its formation age cannot be determined from the photograph.

Uses & applications

Usually a natural specimen, landscaping stone, or craft material; quartzite may be used as aggregate, construction stone, or dimension stone. As shown, it has little jewelry value.

Geological facts

The rounded shape records prolonged transport or wave action, while brown coloration commonly comes from iron oxides. A steel file or knife should not easily scratch a quartz-rich surface.

Field identification & locations

Common worldwide in streambeds and gravel deposits; inspect for visible sand grains, gritty texture, and quartz-rich translucence on a broken edge. A glass-scratching test can support quartz content but is not definitive.