sedimentary

Small ironstone pebble (likely limonite/goethite-rich concretion)

Goethite, α-FeO(OH), with possible limonite and quartz or clay impurities

AI-generated identification · may be incorrect

Small rounded yellow-brown pebble with an earthy to dull luster; likely opaque and fine-grained, with hardness roughly 4–6 and no obvious cleavage. Exact composition cannot be confirmed from the photograph.

Identified October 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Iron-rich minerals precipitated or concentrated during weathering and sedimentary processes, later cementing into a pebble; age and setting cannot be determined from the image.

Uses & applications

Typically collected as a field specimen; ironstone may also be used locally as building stone or as iron ore when sufficiently iron-rich.

Geological facts

Goethite commonly forms through oxidation of iron-bearing minerals and gives soils and rocks yellow, ochre, and brown colors.

Field identification & locations

Look for a dense, rusty-yellow to brown appearance and an ochre streak; a streak test and heft can help distinguish ironstone from ordinary pebbles. Ironstone occurs widely in soils and sedimentary deposits.