sedimentary

Ironstone concretion (possibly a hematite-rich sandstone nodule)

Iron-oxide-cemented sandstone; commonly hematite (Fe₂O₃) and/or goethite (FeO(OH)) cementing quartz grains

AI-generated identification · may be incorrect

Reddish-brown, rough and earthy, with irregular cavities and a dull to submetallic luster; hardness varies, typically about 5–7 Mohs, depending on cement and grain content. The image does not show enough detail to determine its exact mineral proportions or structure.

Identified October 15, 2026More sedimentary →

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At a glance

Common name: Ironstone concretion (possibly a hematite-rich sandstone nodule)
Scientific name: Iron-oxide-cemented sandstone; commonly hematite (Fe₂O₃) and/or goethite (FeO(OH)) cementing quartz grains
Category: sedimentary
Identified: October 15, 2026
Method: Standard

AI Estimated Value

About $1–$20 for a common hand-sized specimen; higher prices require unusual form, locality, or confirmed mineral composition.

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

Iron-rich groundwater can cement sediment into a concretion, often during or after burial in sedimentary layers. Its age and precise formation setting cannot be determined from the photograph.

Uses & applications

Usually collected as a natural specimen; ironstone has limited use as iron ore where iron content is sufficiently high, and some varieties are used as building stone.

Geological facts

The rusty color comes from iron oxides; weathering can produce pits and darker iron-rich patches.

Field identification & locations

Look for a dense, rusty-red to brown nodule, often heavier than ordinary sandstone; a streak test and fresh-surface examination can help distinguish hematite-rich material. Ironstone concretions occur in sedimentary deposits worldwide.