mineral

Limonite Nugget

Limonite (Hydrated iron oxide-hydroxide, FeO(OH)·nH2O)

Hardness: 4 to 5.5 on the Mohs scale. Color: Yellowish-brown, dark brown, to nearly black. Luster: Earthy, submetallic, or silky. Crystal structure: Amorphous, typically occurring as massive, botryoidal, or reniform crusts. Cleavage: None. Specific gravity: 2.7 to 4.3.

Hardness: 4 to 5
Color: Yellowish-brown, dark brown, to nearly black
Luster: Earthy, submetallic, or silky

Identified July 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the oxidation and weathering of primary iron-bearing minerals like pyrite, magnetite, and siderite, often found in gossans and sedimentary iron deposits.

Uses & applications

Historically used as a pigment (ochre), a low-grade iron ore, and as a specimen for mineral collectors.

Geological facts

Limonite is not a true distinct mineral species, but rather a natural mixture of related iron oxides and hydroxides, predominantly goethite, lepidocrocite, and quartz.

Field identification & locations

Can be identified in the field by its characteristic yellowish-brown or brownish-yellow streak and earthy texture. Commonly found in weathered iron-rich zones worldwide.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

sedimentary

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

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Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

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