sedimentary

Hematite / Ironstone

Iron Oxide (Fe2O3)

Hardness 5.5-6.5 on Mohs scale; dark reddish-brown to rust-red color; earthy to metallic luster; non-cleavage; reddish streak; high specific gravity (heavy for its size).

Identified July 21, 2026More sedimentary →

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Physical properties

Hardness 5.5-6.5 on Mohs scale; dark reddish-brown to rust-red color; earthy to metallic luster; non-cleavage; reddish streak; high specific gravity (heavy for its size).

Formation & geological history

Formed through intense chemical weathering of underlying rocks rich in iron minerals under tropical or subtropical conditions, often creating laterite or ironstone deposits.

Uses & applications

Primary ore of iron and steel production; used in red pigments, polishing compounds (rouge), heavy ballast, and as industrial additives.

Geological facts

The reddish-brown dust on Mars is composed of iron oxide, similar to the hematite found in this type of rust-rich ironstone specimen.

Field identification & locations

Identified in the field by its distinct reddish-brown streak test, rough porous surface, high density, and characteristic reddish-orange corrosion coating. Common in deeply weathered terrains worldwide.