sedimentary
Iron Ore (Hematite/Magnetite mixture)
Ferrous Oxide (Fe2O3 / Fe3O4)
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
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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.
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