mineral

Iron-rich hematite/goethite concretion (likely limonite)

Hematite (Fe₂O₃) with goethite (FeO(OH)) and limonite

AI-generated identification · may be incorrect

Identified August 10, 2026More mineral →

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Physical properties

Dark brown to black, strongly earthy-to-metallic luster, irregular massive texture, and apparently very high density; individual crystal faces are not evident. Hematite hardness is about 5–6.5 Mohs; goethite is 5–5.5. A red-brown streak would strongly support hematite, while yellow-brown streak suggests goethite/limonite.

Formation & geological history

Forms by weathering and oxidation of iron-bearing minerals, commonly as nodules or cement in sedimentary deposits. Near 40.1°N, 85.4°W (east-central Indiana), ironstone concretions and glacially transported iron-rich material are plausible; exact age cannot be determined from the photograph.

Uses & applications

Used historically as iron ore and pigment; attractive specimens are collected, but this rough material usually has little commercial value.

Geological facts

Magnetism may be weak or absent; magnetite would be strongly magnetic and typically gives a black streak. The specimen’s rusty metallic appearance is consistent with weathered iron minerals rather than a typical meteorite.

Field identification & locations

Test the streak on unglazed porcelain: hematite leaves red-brown, goethite yellow-brown, and magnetite black. Check density and magnetism; avoid destructive testing until confirmed. Common in iron-rich soils, sedimentary ironstones, and glacial deposits.