mineral

Limonite with Hematite

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Hardness: 4-5.5 (Mohs), Color: Yellowish-brown to black, Luster: Dull to sub-metallic, Crystal structure: Amorphous or microcrystalline, Specific Gravity: 2.7-4.3

Hardness: 4-5

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 4-5.5 (Mohs), Color: Yellowish-brown to black, Luster: Dull to sub-metallic, Crystal structure: Amorphous or microcrystalline, Specific Gravity: 2.7-4.3

Formation & geological history

Formed through the oxidation and hydration of iron-rich mineral deposits (like pyrite or magnetite) in weathered environments. Most common in sedimentary bog iron or secondary enrichment zones.

Uses & applications

Historically used as an iron ore; commonly used as a natural pigment (yellow ochre) in paints, ceramics, and cosmetics. Primarily of interest to mineral collectors.

Geological facts

Limonite is not a true mineral but a mixture of various hydrated iron oxides. It has been used since prehistoric times as a cave painting pigment.

Field identification & locations

Identified by its signature yellow-brown streak, density, and lack of magnetism compared to magnetite. Found globally in weathering zones and hydrothermal vein outcrops.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

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Schist

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Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

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Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic