Rock Identifier
Polished hematite-rich ironstone (Hematite (Fe₂O₃), likely mixed with magnetite and iron-rich jasper) — mineral
mineral

Polished hematite-rich ironstone

Hematite (Fe₂O₃), likely mixed with magnetite and iron-rich jasper

AI-generated identification · may be incorrect

Hardness about 5–6.5 Mohs; metallic to submetallic luster, black with red-brown earthy patches, massive rather than visibly crystalline, and very high density (about 4.5–5.3). The smooth reflective surface appears naturally weathered or polished.

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Physical properties

Hardness about 5–6.5 Mohs; metallic to submetallic luster, black with red-brown earthy patches, massive rather than visibly crystalline, and very high density (about 4.5–5.3). The smooth reflective surface appears naturally weathered or polished.

Formation & geological history

Formed through oxidation and concentration of iron in ancient sedimentary or hydrothermal deposits; associated jasper may be Precambrian in age. Ironstones commonly develop red hematite zones around darker magnetite-rich material.

Uses & applications

Used chiefly as an iron ore, pigment, lapidary material, and collector specimen; attractive polished pieces are sold as ornamental stones rather than gemstones.

Geological facts

The red streak of hematite is diagnostic, even when the specimen looks black; magnetite-rich portions may attract a strong magnet. It is not possible to confirm exact identity from appearance alone.

Field identification & locations

Common in banded iron formations and weathered iron deposits worldwide, especially Australia, Brazil, India, and North America. Test an inconspicuous area for a red-brown streak and measure magnetism; avoid damaging valuable polish.