mineral

Yellow Ochre / Limonite

Limonite (inter-mixed iron oxides and hydroxides, primarily FeO(OH)·nH2O)

AI-generated identification · may be incorrect

Hardness: 4-5.5 | Color: Yellowish-brown to ochre yellow | Luster: Dull/Earthy | Crystal Structure: Amorphous/Microcrystalline | Streak: Yellowish-brown

Hardness: 4-5
Streak: Yellowish-brown

Identified April 3, 2026More mineral →

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Physical properties

Hardness: 4-5.5 | Color: Yellowish-brown to ochre yellow | Luster: Dull/Earthy | Crystal Structure: Amorphous/Microcrystalline | Streak: Yellowish-brown

Formation & geological history

Formed as a secondary material through the oxidation or weathering of iron-rich minerals such as pyrite, magnetite, and siderite. Often occurs in the oxidized zones of ore deposits.

Uses & applications

Historically used as a natural earth pigment (Yellow Ochre) for art; also used as a minor iron ore and in some traditional cement manufacturing.

Geological facts

Ochre is one of the oldest pigments used by mankind, appearing in cave paintings dating back over 30,000 years. Limonite is not a 'true' mineral but a mixture of hydrated iron oxide minerals like goethite.

Field identification & locations

Identify by its distinctive yellow-brown 'mustard' color and dull, earthy texture. It will leave a brownish-yellow streak on an unglazed porcelain plate. Commonly found in swamps (bog iron) or near weathered iron outcrops.