mineral
Botryoidal hematite or iron-oxide ore
Hematite, Fe₂O₃, possibly mixed with goethite/limonite
AI-generated identification · may be incorrectDark steel-gray to black, strongly metallic-to-submetallic luster, irregular botryoidal texture, and no obvious cleavage; hematite hardness is about 5–6.5 Mohs and specific gravity about 5.0–5.3. The appearance is consistent with a dense iron-oxide specimen, though the photograph cannot confirm composition.
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Physical properties
Dark steel-gray to black, strongly metallic-to-submetallic luster, irregular botryoidal texture, and no obvious cleavage; hematite hardness is about 5–6.5 Mohs and specific gravity about 5.0–5.3. The appearance is consistent with a dense iron-oxide specimen, though the photograph cannot confirm composition.
Formation & geological history
Typically forms by oxidation and hydrothermal alteration of iron-bearing rocks, often as botryoidal crusts or replacement masses; specimens may range from ancient Precambrian ores to younger weathering deposits. Common localities include Brazil, Morocco, the United States, and Australia.
Uses & applications
Used as an iron ore and pigment; attractive botryoidal pieces are collected and occasionally polished for display. It is generally inexpensive unless exceptionally lustrous, well formed, or locality-documented.
Geological facts
Hematite produces a diagnostic red-to-reddish-brown streak even when its surface is black and metallic. Goethite-rich material may produce a yellow-brown streak and has slightly lower hardness.
Field identification & locations
Test an inconspicuous spot with an unglazed porcelain tile for streak, examine density, and use a magnet cautiously because hematite is usually weakly magnetic while magnetite is strongly magnetic. The specimen’s lumpy metallic surface favors botryoidal hematite, but laboratory testing would be needed for certainty.
