sedimentary

Sandy Ironstone

Ferruginous Sandstone

Hardness: 6-7 (Mohs scale), Color: Reddish-brown to tan with metallic glints, Luster: Dull to sub-metallic, Crystal Structure: Clastic grains cemented by iron oxides, Cleavage: None, Specific Gravity: 2.8 - 3.4

Identified May 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed by the precipitation of iron oxides (hematite or goethite) within sandstone layers. Often occurs as concretions or crusts in sedimentary basins and arid environments.

Uses & applications

Used primarily as low-grade iron ore, road fill, and sometimes as a decorative building stone. Highly valued by amateur rockhounds and fossil hunters as it often encases organic matter.

Geological facts

Ironstone is often much heavier and harder than surrounding sandstone due to its dense iron mineral content. It can form weird, sculptural shapes called concretions that people often mistake for artifacts or meteorites.

Field identification & locations

Identify by its distinctive rust-red to dark brown color and high density compared to normal sandstone. Commonly found in streambeds, desert pavements, and coastal cliffs. Use a magnet to check for hematite/magnetite presence.