Rock Identifier
Botryoidal hematite/goethite specimen (Hematite (Fe₂O₃), likely with goethite (FeO(OH)) and minor limonite) — mineral
mineral

Botryoidal hematite/goethite specimen

Hematite (Fe₂O₃), likely with goethite (FeO(OH)) and minor limonite

AI-generated identification · may be incorrect

Dark steel-gray to reddish-brown, botryoidal and reniform surface with metallic to submetallic luster; hardness about 5–6.5 Mohs, no obvious cleavage, dense, and typically massive rather than visibly crystalline. Hematite streak is diagnostic reddish-brown to red.

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Physical properties

Dark steel-gray to reddish-brown, botryoidal and reniform surface with metallic to submetallic luster; hardness about 5–6.5 Mohs, no obvious cleavage, dense, and typically massive rather than visibly crystalline. Hematite streak is diagnostic reddish-brown to red.

Formation & geological history

Forms through oxidation and precipitation of iron-rich fluids, commonly coating cavities or replacing host rock; goethite/limonite commonly develops during weathering. Deposits range from ancient Precambrian iron formations to young weathering environments.

Uses & applications

Used as an iron ore and pigment; attractive botryoidal pieces are collected and occasionally used in lapidary work, though they are generally not gem-quality.

Geological facts

The specimen’s rounded, kidney-like growths are characteristic of botryoidal iron oxides. A streak test on unglazed porcelain is more reliable than color: hematite leaves a red-brown streak, while magnetism is usually weak or absent.

Field identification & locations

Common in iron-rich zones, hydrothermal veins, caves, and weathered sulfide deposits worldwide, especially Brazil, Morocco, England, and the United States. Confirm with streak, high density, and possible rusty-brown powder; visual identification is not definitive without testing.