mineral

Hematite-rich ironstone concretion

Hematite (Fe₂O₃), likely mixed with goethite/limonite and silica

AI-generated identification · may be incorrect

Dark reddish-brown, earthy to submetallic luster, massive and porous with an irregular cavity; hematite hardness 5–6.5 Mohs, specific gravity about 5.0–5.3, with no visible cleavage. A red-brown streak on unglazed ceramic is diagnostic.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed as a weathering or sedimentary iron-oxide concretion, where iron minerals precipitated and cemented surrounding sediment; age cannot be determined from the photograph. The cavity may reflect dissolution, gas space, or removal of softer material.

Uses & applications

Iron oxides are mined as iron ore and used as pigments; attractive specimens are collected, though this irregular piece has little industrial or jewelry value.

Geological facts

Hematite commonly produces a distinctive red streak even when its surface appears black or brown. Goethite-rich varieties may develop yellow-brown earthy coatings.

Field identification & locations

Common in weathered iron-rich soils, banded iron formations, stream gravels, and sedimentary deposits worldwide. Test streak and magnetism: hematite is usually nonmagnetic or weakly magnetic, while associated magnetite is strongly magnetic.