sedimentary

Banded Iron Formation (Jasper-grade)

Banded Iron Formation (BIF) containing Hematite/Magnetite and Chert (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Reddish-brown with creamy white or gray bands, Luster: Dull to sub-vitreous, Crystal structure: Microcrystalline/Cryptocrystalline, Specific Gravity: 2.6-3.3

Hardness: 6

Identified May 27, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Reddish-brown with creamy white or gray bands, Luster: Dull to sub-vitreous, Crystal structure: Microcrystalline/Cryptocrystalline, Specific Gravity: 2.6-3.3

Formation & geological history

Formed in ancient marine environments between 2.4 and 1.8 billion years ago (Proterozoic Eon) through the precipitation of iron and silica during the Great Oxidation Event.

Uses & applications

Used primarily as iron ore for steel production; also used for lapidary work, jewelry, and as a collector's specimen.

Geological facts

These formations provide the primary evidence for the evolution of Earth's atmosphere and the introduction of free oxygen by early life forms like cyanobacteria.

Field identification & locations

Identify by the alternating thin layers (banding) of iron oxides and silica. Common in old shield regions like the Lake Superior area, Australia, and Brazil.