sedimentary

Iron Ore (Hematite/Magnetite mixture)

Ferrous Oxide (Fe2O3 / Fe3O4)

AI-generated identification · may be incorrect

Hardness: 5.5-6.5; Color: Steel-gray to black with reddish-brown oxidation; Luster: Metallic to sub-metallic; Crystal Structure: Trigonal/Isometric; Specific Gravity: 4.9-5.3

Hardness: 5
Color: Steel-gray to black with reddish-brown oxidation
Luster: Metallic to sub-metallic

Identified April 24, 2026More sedimentary →

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Physical properties

Hardness: 5.5-6.5; Color: Steel-gray to black with reddish-brown oxidation; Luster: Metallic to sub-metallic; Crystal Structure: Trigonal/Isometric; Specific Gravity: 4.9-5.3

Formation & geological history

Primary formation typically occurs in Banded Iron Formations (BIFs) where iron-rich minerals precipitated from seawater due to rising oxygen levels (Great Oxidation Event) roughly 2.4 to 1.8 billion years ago.

Uses & applications

Primary source of iron for steel production; used in pigments, radiation shielding, and as a weighting agent in drilling fluids.

Geological facts

Banded iron formations provide critical evidence for the evolution of the Earth's atmosphere, marking the transition from an anaerobic to an oxygen-rich environment.

Field identification & locations

Identify using a streak test; hematite-rich ore will leave a reddish-brown streak even if the stone looks black. Found in massive deposits in Australia, Brazil, and the Lake Superior region.