mineral
Limonite/goethite-rich ironstone
Hydrated iron oxides, chiefly goethite (α-FeO(OH)) and limonite (FeO(OH)·nH₂O)
AI-generated identification · may be incorrectYellow-brown, earthy to dull luster, opaque, and typically massive with no visible crystals; hardness about 4–5.5 Mohs, variable density, and commonly leaves a yellow-brown streak.
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Physical properties
Yellow-brown, earthy to dull luster, opaque, and typically massive with no visible crystals; hardness about 4–5.5 Mohs, variable density, and commonly leaves a yellow-brown streak.
Formation & geological history
Forms through weathering and oxidation of iron-bearing rocks or sulfide deposits, often as a gossan or lateritic residual material; age depends on the host deposit and may range from recent weathering to ancient ore formation.
Uses & applications
Used as a low-grade iron ore, natural ochre pigment, and collector specimen; compact examples may be polished decoratively but are generally not gemstone material.
Geological facts
The bright yellow color may reflect goethite, jarosite, or other iron minerals; limonite is a field term rather than a single precisely defined mineral species.
Field identification & locations
Identify by its earthy yellow-brown color, heavy feel, rusty coating, and yellow-brown streak; common in weathered iron deposits worldwide. Acid testing and laboratory methods are needed to distinguish it confidently from sulfur-bearing minerals or altered rock.
