Rock Identifier
Dark tumbled mineral/rock fragment (tentatively hematite-rich material) (Likely hematite (Fe₂O₃), possibly magnetite-bearing ironstone) — mineral
mineral

Dark tumbled mineral/rock fragment (tentatively hematite-rich material)

Likely hematite (Fe₂O₃), possibly magnetite-bearing ironstone

AI-generated identification · may be incorrect

Opaque dark gray to reddish-brown, submetallic to dull luster, irregular rounded surfaces, and no obvious cleavage; hematite hardness is about 5–6.5 Mohs (magnetite about 5.5–6.5), with specific gravity roughly 5.0–5.3. Image alone cannot confirm streak or magnetism.

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Physical properties

Opaque dark gray to reddish-brown, submetallic to dull luster, irregular rounded surfaces, and no obvious cleavage; hematite hardness is about 5–6.5 Mohs (magnetite about 5.5–6.5), with specific gravity roughly 5.0–5.3. Image alone cannot confirm streak or magnetism.

Formation & geological history

Iron oxides form through oxidation and concentration of iron in sedimentary, hydrothermal, or weathering environments; hematite deposits range from Precambrian banded iron formations to younger weathering crusts. The rounded shape suggests natural abrasion or tumbling.

Uses & applications

Hematite is an iron ore, pigment, and common lapidary/collecting material; polished pieces are used in jewelry and ornaments.

Geological facts

Hematite typically leaves a distinctive red to reddish-brown streak, whereas magnetite leaves a black streak and is strongly magnetic.

Field identification & locations

Test an inconspicuous area with an unglazed ceramic tile for streak and use a magnet; a red streak favors hematite, strong attraction favors magnetite. Common sources include Brazil, Australia, Canada, India, and the United States.