Iron Ore (Limonite and Hematite)

Physical Properties

Hardness: 4.0-5.5; Color: Yellow-brown to blackish; Luster: Dull, earthy to sub-metallic; Crystal Structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7-4.3

Formation & Geological History

Formed primarily through the weathering and oxidation of iron-rich minerals in sedimentary deposits, or as a secondary mineral in the gossans of metallic ore deposits.

Uses & Applications

Primary source of iron for steel manufacturing; used as a pigment (ochre) in paints, coatings, and concrete; occasionally used as a filler in drilling mud.

Geological Facts

Limonite is not a true mineral but a mixture of hydrated iron oxide minerals. It was historically one of the most important sources of iron for early humans and used as a natural pigment since pre-history.

Field Identification & Locations

Identified by its distinctive yellow-brown to rusty streak and earthy appearance. Found globally in bog deposits, weathered iron-rich rocks, and mining tailings.

Identified on: 5/13/2026

Mode: Standard