Distinctive Precambrian sedimentary rock with alternating layers of iron-rich hematite/magnetite and silica-rich chert bands. Texture: Banded alternating iron and silica layers. Rock type: Sedimentary Chemical. Grain size: Fine. Minerals present: Hematite, Magnetite, Chert, Jasper. Formation: Formed 2.5-1.8 billion years ago when dissolved iron in anoxic oceans was oxidized by early photosynthetic organisms. Common geological settings: Western Australia Hamersley , Brazil Carajás , South Africa, Labrador; major iron ore source. Common look-alikes and related entries: Ironstone, Jasper, Tiger Iron.
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Banded rocks — Place this specimen in a broader field-identification workflow.
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GeoMiner
Last updated
2026-03-30T14:38:33.792687+00:00
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Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
Distinctive Precambrian sedimentary rock with alternating layers of iron-rich hematite/magnetite and silica-rich chert bands.
How can you identify Banded Iron Formation?
Compare several properties rather than relying on colour alone. This entry records rock type: Sedimentary Chemical; texture: Banded alternating iron and silica layers; grain size: Fine; common minerals: Hematite, Magnetite, Chert, Jasper. Confirm an important identification with additional field tests or qualified laboratory work.
How does Banded Iron Formation form?
Formed 2.5-1.8 billion years ago when dissolved iron in anoxic oceans was oxidized by early photosynthetic organisms.
Where is Banded Iron Formation commonly found?
Western Australia Hamersley , Brazil Carajás , South Africa, Labrador; major iron ore source.
What is Banded Iron Formation commonly confused with?
Banded Iron Formation may be confused with Ironstone, Jasper, Tiger Iron. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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