sedimentary

Yellow Ochre (Limonite)

Limonite (FeO(OH)qnH2O)

Hardness: 4-5.5 (Mohs scale), Color: dull yellow to brownish-yellow, Luster: earthy to dull, Crystal Structure: amorphous (microcrystalline), Cleavage: absent, Specific Gravity: 2.7-4.3

Hardness: 4-5

Identified July 12, 2026More sedimentary →

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Physical properties

Hardness: 4-5.5 (Mohs scale), Color: dull yellow to brownish-yellow, Luster: earthy to dull, Crystal Structure: amorphous (microcrystalline), Cleavage: absent, Specific Gravity: 2.7-4.3

Formation & geological history

Formed as a secondary mineral through the weathering and oxidation of iron-rich minerals (such as pyrite or magnetite) in sedimentary environments, often found in bog deposits or iron hats (gossans).

Uses & applications

Primarily used as a natural pigment for paint, dyes, and cosmetics. Historically used for cave paintings and pottery glazes.

Geological facts

Yellow ochre is one of the oldest pigments used by humans, dating back over 70,000 years. It is essentially rust mixed with clay and sand.

Field identification & locations

Identify by its characteristic yellow-brown streak (powder) and earthy texture. Commonly found in weathered iron ore deposits globally. Collectors look for rich, consistent coloration.