mineral

Limonite (Iron Ore / Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

AI-generated identification · may be incorrect

Mohs hardness 4.0-5.5, dull to earthy luster, vibrant yellowish-brown to rust-orange color, amorphous structure, specific gravity around 2.7-4.3

Identified July 26, 2026More mineral →

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Physical properties

Mohs hardness 4.0-5.5, dull to earthy luster, vibrant yellowish-brown to rust-orange color, amorphous structure, specific gravity around 2.7-4.3

Formation & geological history

Formed as a secondary mineral through the weathering and oxidation of iron-rich primary minerals such as pyrite, magnetite, and hematite in near-surface geological environments.

Uses & applications

Historically used as an important iron ore and as a natural earth pigment (yellow/brown ochre) for paints, cosmetics, and dyes.

Geological facts

Limonite is technically not a true single mineral but a mixture of hydrated iron oxide minerals, predominantly goethite with varying amounts of lepidocrocite, jarosite, and clay.

Field identification & locations

Identified by its characteristic yellowish-brown streak, earthy rust-like appearance, and light weight relative to hematite. Commonly found in oxidized zones of mineral deposits globally.