sedimentary

Polished ironstone concretion with quartz/iron-oxide vein

Goethite–hematite-rich ironstone concretion, likely veined by quartz or chalcedony

AI-generated identification · may be incorrect

Dark gray-black, rounded and highly polished, with a rusty orange-brown vein. Likely Mohs hardness 5–7, submetallic to dull luster, massive rather than crystalline, and high specific gravity (~3–4); cleavage is absent.

Identified August 16, 2026More sedimentary →

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At a glance

Common name: Polished ironstone concretion with quartz/iron-oxide vein
Scientific name: Goethite–hematite-rich ironstone concretion, likely veined by quartz or chalcedony
Category: sedimentary
Identified: August 16, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small polished common specimen; potentially $40–$100 if unusually attractive, heavy, or provenance-documented.

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

Probably formed as an iron-rich concretion in sediment, later fractured and filled by silica and oxidized iron minerals. Its exact geological age cannot be determined from the photograph; similar concretions occur in many sedimentary formations.

Uses & applications

Primarily a lapidary and collecting specimen; polished pieces may be used as display stones or paperweights, but it has little industrial value in this form.

Geological facts

The dark material is consistent with hematite, magnetite, or goethite-rich ironstone, while the orange vein may contain limonite/goethite and iron-stained silica.

Field identification & locations

Identify it by its unusually heavy feel, dark opaque surface, rounded concretion shape, and contrasting rusty fracture vein; a streak test and magnet test would help distinguish hematite from magnetite. Common examples occur in iron-rich sedimentary terrains worldwide.