Banded iron formation
Rock made of hematite, magnetite, quartz
Common
Thin alternating layers of silver to black iron oxide and red chert, up to hundreds of metres thick and hundreds of kilometres long. Almost all are Precambrian, and they hold more than three fifths of the world’s iron reserves.
Rock
- Kind of rock
- Chemical sedimentary rock
- Rock family
- Sandstone, shale and clay
- Texture
- banded
- Also contains
- Siderite
- Deposits
- Banded iron formation deposit
- Metals
- Iron
- Shapes the land into
- Plateau
- How it forms
- Oxygen made by early cyanobacteria met the iron dissolved in the oceans and rained iron oxide onto the sea floor, band by band.
- Uses
- Most of the iron ore mined today, first found in northern Michigan in 1844.
Identity
- Also known as
- BIF, Banded ironstone, Jaspilite
Crystallography
- Habits
- Massive
Physical properties
- Luster
- Metallic, Dull
- Colors
- silver gray, black, red
- Transparency
- Opaque
Geology
- Origins
- Sedimentary
- Geography
- Australia (Hamersley Range), Brazil, Canada, India, Russia, South Africa, Ukraine, USA (Mesabi Range, Minnesota)
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- Banded iron formation. Wikipedia.
- Chert. Wikipedia.
- C. R. Hallsworth, R. W. O’B. Knox, BGS Rock Classification Scheme, Volume 3: Classification of sediments and sedimentary rocks (Research Report RR 99-03). British Geological Survey, 1999.
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