mineral

Botryoidal goethite/limonite specimen

Goethite (α-FeO(OH)), commonly mixed with limonite and iron oxides

AI-generated identification · may be incorrect

Dark brown to black, earthy-to-submetallic luster with rounded botryoidal surfaces; hardness about 5–5.5 Mohs, uneven fracture, no prominent cleavage, and specific gravity roughly 3.3–4.3. The rusty brown-gold appearance is typical of hydrated iron oxides.

Identified September 5, 2026More mineral →

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Physical properties

Formation & geological history

Forms as a secondary mineral through oxidation and weathering of iron-bearing sulfides or other iron minerals, commonly in hydrothermal veins, caves, and soil or ore zones. Its age depends on the deposit and may range from recent weathering to ancient ore formation.

Uses & applications

Used as an iron ore and historically as a brown-yellow pigment; attractive botryoidal pieces are collected as cabinet specimens, though it is not generally a gemstone.

Geological facts

Goethite commonly occurs with hematite, limonite, quartz, and sulfides; “limonite” is a field term for poorly crystalline hydrated iron oxides rather than one specific mineral.

Field identification & locations

Identify by heavy feel, brown-black botryoidal texture, and usually yellow-brown streak; a streak test and specific-gravity measurement would distinguish it from hematite, slag, or sulfides. Common worldwide in oxidized iron deposits.