mineral
Limonite Geode / Ironstone Nodule
Hydrated Iron Oxide Hydroxide (FeO(OH)·nH2O)
Hardness varies from 4 to 5.5 on the Mohs scale, color ranges from yellowish-brown, dark brown to black, luster is submetallic to earthy, amorphous or microcrystalline structure, specific gravity is 2.7 to 4.3.
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Physical properties
Hardness varies from 4 to 5.5 on the Mohs scale, color ranges from yellowish-brown, dark brown to black, luster is submetallic to earthy, amorphous or microcrystalline structure, specific gravity is 2.7 to 4.3.
Formation & geological history
Formed by the weathering and oxidation of iron-bearing sulfide minerals, silicates, and carbonates in sedimentary environments or hydrothermal veins.
Uses & applications
Used historically as an iron ore, a pigment (ochre), and as a mineral specimen for collectors.
Geological facts
Limonite is not a true distinct mineral species, but rather a catch-all term for natural mixtures of iron oxide minerals, mostly goethite, lepidocrocite, and hematite.
Field identification & locations
Identified by its characteristic yellowish-brown streak, earthy texture, and hollow nodular form containing secondary mineral linings. Found worldwide.
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Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
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Septarian Pebble
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