mineral
Tumbled iron-rich stone, likely hematite-bearing rock
Hematite (Fe₂O₃), possibly mixed with magnetite/goethite and host rock
AI-generated identification · may be incorrectDark brown to steel-gray, metallic-to-submetallic luster, opaque, smoothly polished; hematite hardness about 5–6.5 Mohs, no prominent cleavage, specific gravity about 5.0–5.3. The rounded shape indicates human tumbling or natural abrasion.
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Physical properties
Dark brown to steel-gray, metallic-to-submetallic luster, opaque, smoothly polished; hematite hardness about 5–6.5 Mohs, no prominent cleavage, specific gravity about 5.0–5.3. The rounded shape indicates human tumbling or natural abrasion.
Formation & geological history
Iron oxides form by oxidation of iron-rich rocks and hydrothermal, sedimentary, or weathering processes; hematite deposits range from Precambrian banded iron formations to much younger weathering zones. Exact age and locality cannot be determined from the photograph.
Uses & applications
Used as an iron ore, pigment, polishing abrasive, and ornamental stone; attractive specimens are sold as tumbled stones or carved jewelry pieces.
Geological facts
Hematite’s red-brown streak is diagnostic, even when the surface appears black or metallic. Magnetism would suggest appreciable magnetite rather than pure hematite.
Field identification & locations
Test an inconspicuous area for a reddish-brown streak on unglazed porcelain; hematite is weakly or nonmagnetic, while magnetite is strongly magnetic. Common sources include Brazil, Australia, India, the United States, and South Africa.
