sedimentary
Banded Iron Formation (Jasper-grade)
Banded Iron Formation (BIF) containing Hematite/Magnetite and Chert (SiO2)
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 More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
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.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite
sedimentary