mineral

Limonite with Quartz

FeO(OH)·nH2O (Limonite) with SiO2 (Quartz)

Hardness: 4-5.5 (Limonite) and 7 (Quartz); Color: Yellowish-brown, ochre, or dark brown; Luster: Earthy to submetallic; Crystal Structure: Amorphous or cryptocrystalline; Cleavage: None; Specific Gravity: 2.7-4.3.

Hardness: 4-5
Color: Yellowish-brown, ochre, or dark brown
Luster: Earthy to submetallic

Identified June 6, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral through the oxidation and hydration of iron-rich minerals such as pyrite or magnetite. Often found in gossipans (weathered rock covering ore deposits) or bog environments.

Uses & applications

Historically used as a major iron ore and as a source of yellow ochre pigment. Currently mainly of interest to collectors and geological researchers as an indicator of underlying metal deposits.

Geological facts

Limonite is not a single mineral but a mixture of hydrated iron oxide minerals, primarily goethite. It was used by ancient civilizations for cave paintings and pottery dyes dating back thousands of years.

Field identification & locations

Identify by its distinctive yellow-brown streak, earthy appearance, and lack of magnetism compared to magnetite. Commonly found in areas with heavy rain where iron minerals are prone to chemical weathering. Check for nearby quartz veins.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

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Schist

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Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

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Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

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