mineral

Tumbled dark metallic mineral specimen

Likely hematite or magnetite; identification is uncertain from the photograph

AI-generated identification · may be incorrect

Small, rounded, dark gray-black piece with a metallic to submetallic luster and irregular fracture. Hematite has Mohs hardness 5–6.5 and reddish-brown streak; magnetite has hardness 5.5–6.5 and is strongly magnetic.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Iron oxides formed in hydrothermal veins, igneous rocks, or sedimentary iron formations over geologic time. Tumbled edges indicate human polishing or abrasion.

Uses & applications

Hematite is used as an iron ore, pigment, and jewelry stone; magnetite is an important iron ore and industrial mineral. Common tumbled pieces are mainly collectible.

Geological facts

A streak test is especially diagnostic: hematite leaves a red to reddish-brown streak, while magnetite leaves a black streak. Magnetite should attract a strong magnet; hematite generally does not, though some specimens are weakly magnetic.

Field identification & locations

Common localities include Brazil, Australia, India, South Africa, and the United States. Test magnetism and streak on unglazed porcelain; avoid relying on appearance alone because polished slag and other metallic minerals can look similar.