mineral

Goethite–limonite ironstone

Goethite (α-FeO(OH)) with limonite, hydrated iron oxides, and possible quartz

AI-generated identification · may be incorrect

Brown, ochre, black, and rusty-orange botryoidal or porous surface; earthy to submetallic luster, typically opaque, with hardness about 4–5.5 for goethite and variable hardness in limonite; no obvious cleavage.

Identified August 27, 2026More mineral →

Explore Goethite–limonite ironstone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms through oxidation and weathering of iron-bearing minerals, commonly as gossan, laterite, cavity coatings, or hydrothermal replacement. Usually geologically young relative to its parent rock, though it can form in deposits of many ages.

Uses & applications

Used as an iron ore and historically as ochre pigment; attractive botryoidal pieces are collected, but this specimen is generally not jewelry grade.

Geological facts

The rusty color results from hydrated iron oxides; goethite may produce iridescent or velvety surfaces and is commonly associated with hematite, quartz, and sulfide-ore weathering.

Field identification & locations

Identify by its rusty streak, high apparent density, earthy/botryoidal texture, and strong yellow-brown to brown-black powder; it may weakly attract a magnet if hematite or magnetite is present. Common in weathered iron deposits worldwide, including Australia, Brazil, India, and the United States.