sedimentary

Water-worn ironstone pebble (probable concretion)

Ferruginous sandstone or iron-rich mudstone concretion; chiefly quartz and iron oxides/hydroxides (hematite, goethite, limonite)

AI-generated identification · may be incorrect

Hardness about 5–7 Mohs; ochre-brown, fine-grained, dull to earthy luster, with rounded surfaces from abrasion. The white circular patches may be quartz/calcite veins or weathered inclusions; crystal structure is mostly microscopic and cleavage is absent or indistinct.

Identified September 5, 2026More sedimentary →

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At a glance

Common name: Water-worn ironstone pebble (probable concretion)
Scientific name: Ferruginous sandstone or iron-rich mudstone concretion; chiefly quartz and iron oxides/hydroxides (hematite, goethite, limonite)
Category: sedimentary
Identified: September 5, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 as an ordinary pebble; perhaps $10–$30 if unusually patterned, locality-documented, or strongly magnetic.

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 when iron-bearing groundwater cemented sand or mud around inclusions, followed by uplift, weathering, and stream or beach abrasion. Its precise geological age cannot be determined from the photograph.

Uses & applications

Primarily a curiosity or teaching specimen; ironstone may be used locally as aggregate or low-grade iron ore, but this pebble has little industrial or jewelry value.

Geological facts

Iron oxides produce the brown-yellow coloration and commonly create concentric or irregular cemented textures. A streak test on unglazed ceramic may show yellow-brown to reddish-brown powder.

Field identification & locations

Common in streambeds, beaches, weathered sedimentary terrains, and lateritic soils. Check for a rusty streak, weak attraction to a magnet, and fizzing only if white areas are calcite; acid testing should be cautious.