mineral

Limonite (often after Hematite or Goethite)

Limonite (FeO(OH)·nH2O)

Hardness: 4-5.5; Color: Yellow-brown, orange-brown, or dark brown; Luster: Dull or earthy; Crystal structure: Amorphous to microcrystalline; Streak: Yellowish-brown; Specific Gravity: 2.7–4.3.

Hardness: 4-5
Color: Yellow-brown, orange-brown, or dark brown
Luster: Dull or earthy

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 4-5.5; Color: Yellow-brown, orange-brown, or dark brown; Luster: Dull or earthy; Crystal structure: Amorphous to microcrystalline; Streak: Yellowish-brown; Specific Gravity: 2.7–4.3.

Formation & geological history

Formed as a secondary mineral through the weathering of iron-rich minerals such as hematite, magnetite, or pyrite. It is frequently found in the oxidation zones of ore deposits and as a precipitate in bogs and springs.

Uses & applications

Historically used as an iron ore; currently used primarily as a pigment (yellow ochre) in paints, dyes, and cosmetics. It is also of interest to amateur rock collectors.

Geological facts

Limonite is not a true mineral species but a mixture of hydrated iron oxide minerals, primarily goethite. It was one of the earliest pigments used by humans, found in cave paintings dating back tens of thousands of years.

Field identification & locations

Identify by its distinctive yellowish-brown streak on a ceramic plate and its earthy, rusted appearance. Often found in sedimentary settings or weathered outcrops. It often forms 'pseudomorphs,' where it takes the crystal shape of the mineral it replaced.

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