sedimentary or metamorphic

Smooth river pebble, likely quartz-rich sandstone or quartzite

Indeterminate quartz-rich clast; possibly quartzite (mostly SiO₂)

AI-generated identification · may be incorrect

Rounded, water-worn, fine-grained tan-brown surface with dull to faintly silky luster; no visible crystals or cleavage. Likely hardness about 6–7 Mohs if quartz-rich, with moderate-to-high density around 2.5–2.7 g/cm³.

Identified September 12, 2026More sedimentary or metamorphic →

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At a glance

Common name: Smooth river pebble, likely quartz-rich sandstone or quartzite
Scientific name: Indeterminate quartz-rich clast; possibly quartzite (mostly SiO₂)
Category: sedimentary or metamorphic
Identified: September 12, 2026
Method: Standard

AI Estimated Value

About $0–$5 as an ordinary pebble; roughly $5–$20 if unusually attractive, polished, or locally significant.

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

Most likely a river or beach cobble shaped by abrasion and weathering. If quartzite, it formed when quartz sandstone was metamorphosed; if sandstone, it lithified from deposited sand, commonly during the Precambrian–Cenozoic depending on source terrain.

Uses & applications

Usually collected as a natural curiosity, paperweight, or landscaping material; quartzite can be used as aggregate, paving stone, and building stone. It has little gemstone value unless it displays unusual color or pattern.

Geological facts

The uniformly smooth, oval form indicates prolonged transport in moving water or wave action. Surface color may result from iron-oxide staining.

Field identification & locations

Test with a steel knife or glass: quartz-rich material should resist scratching glass and may scratch steel. A streak test, fresh broken surface, and acid test would help distinguish quartzite from softer sandstone or limestone; common in streambeds worldwide.