mineral

Limonite Concretion

Hydrated Iron Oxide-Hydroxide, FeO(OH)*nH2O

Hardness of 4-5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, and amorphous crystal structure.

Identified October 23, 2026More mineral →

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Physical properties

Hardness of 4-5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, and amorphous crystal structure.

Formed through the secondary oxidation and weathering of iron-bearing minerals in sedimentary environments.

Historically used as a pigment (ochre) and minor iron ore; primarily sought by mineral collectors.

Limonite is not a true distinct mineral species, but rather a natural mixture of related iron oxides like goethite and lepidocrocite.

Identified by its characteristic yellowish-brown streak and earthy appearance, commonly found in weathering zones worldwide.

Gneiss or Schist

Gneiss or Mica Schist with Garnet

Limonite

FeO(OH)•nH2O

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

Feldspar

Feldspar Group (Tectosilicate, e.g., KAlSi3O8)

Tumbled granite

Granite, a coarse-grained felsic intrusive igneous rock

Pegmatite with Tourmaline and Quartz

Igneous Pegmatite