sedimentary

Banded river pebble, likely dark chert or fine-grained quartzite

Chert (microcrystalline quartz, SiO₂) or quartzite; exact identification requires testing

AI-generated identification · may be incorrect

Rounded, smooth dark-brown pebble with subtle curved bands. If chert, hardness is about 7 Mohs, vitreous to waxy luster, and no cleavage; a quartzite alternative is also typically near 7 Mohs.

Identified October 9, 2026More sedimentary →

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At a glance

Common name: Banded river pebble, likely dark chert or fine-grained quartzite
Scientific name: Chert (microcrystalline quartz, SiO₂) or quartzite; exact identification requires testing
Category: sedimentary
Identified: October 9, 2026
Method: Standard

AI Estimated Value

About $0–$5 as a common pebble; more only if identified, unusually patterned, or sold as part of a curated collection.

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

Rounded, smooth dark-brown pebble with subtle curved bands. If chert, hardness is about 7 Mohs, vitreous to waxy luster, and no cleavage; a quartzite alternative is also typically near 7 Mohs.

Formation & geological history

Likely shaped by transport in water; chert forms from silica-rich sediment, while quartzite forms when sandstone is metamorphosed. The image does not establish its geological age or exact origin.

Uses & applications

Primarily a natural collectible or decorative pebble; chert has historically been used for tools, while quartzite is used as aggregate and dimension stone.

Geological facts

The smooth shape and muted bands are consistent with prolonged abrasion, but appearance alone cannot reliably distinguish chert from quartzite or other dark rocks.

Field identification & locations

Look for a glassy or waxy surface and conchoidal fracture to support chert; quartzite commonly shows fused, sugary quartz grains. No locality can be determined from the image.