sedimentary

Iron-rich concretion or weathered ironstone pebble

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

AI-generated identification · may be incorrect

Hardness about 5–6.5 Mohs; ochre-orange to brown with dark gray-brown bands, earthy to dull luster, and massive non-crystalline texture. The rounded shape and rusty coloration indicate iron-oxide cementation rather than a true crystal.

Identified August 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when groundwater precipitated iron oxides around a nucleus in sediment, later weathering into a resistant rounded pebble; exact age cannot be determined from the photograph. Such concretions commonly form in soils, sedimentary rocks, and weathered iron-bearing zones.

Uses & applications

Used mainly as a collectible or teaching specimen; ironstone and goethite ores may be mined for iron pigment or iron, but this small piece has no practical industrial value.

Geological facts

Dark bands may reflect changing groundwater chemistry or layered growth. A strong reddish-brown streak on unglazed porcelain would support hematite/goethite identification.

Field identification & locations

Common in iron-rich soils and sedimentary terrains worldwide, including Australia, Brazil, India, and the United States. Test for a yellow-brown to red streak, moderate heft, and absence of fizz with dilute acid; a magnet may show weak attraction if magnetite is present.