sedimentary

Weathered iron-rich concretion or ironstone pebble

Goethite/hematite-bearing limonite concretion (approximate identification)

AI-generated identification · may be incorrect

Gray-brown, dull to earthy luster, rounded and heavily weathered; likely hardness about 4–6 Mohs with moderate-to-high density. The porous, granular surface and dark metallic-looking patches suggest iron oxides rather than a crystalline gemstone.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when iron minerals cemented sediment around a nucleus, followed by weathering and stream or soil transport; exact age and setting cannot be determined from the photograph.

Uses & applications

Usually a common field specimen with little commercial use, though ironstone may be used as low-grade iron ore, aggregate, or landscape material.

Geological facts

Iron-rich concretions commonly develop rusty red, brown, yellow, gray, or black colors. A reddish-brown streak and attraction to a strong magnet would help distinguish ironstone from ordinary gray pebbles.

Field identification & locations

Common in sedimentary terrains, soils, stream gravels, and glacial deposits worldwide. Test with a steel nail, streak it on unglazed ceramic, and inspect a fresh break; a magnet may show weak attraction if magnetite is present.