Definition
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Anorthosite is a granular igneous rock composed largely of labradorite or plagioclase
History
Origin
Western Australia, Minnesota
-
Discoverer
Johann Gottlob Lehmann
Unknown
Etymology
From its formation process
From French anorthose plagioclase + -ite1
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
Plutonic
Other Categories
Coarse Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Banded, Trellis
Foliated, Glassy
Color
Red, Reddish Brown
Black, Bluish - Grey, Brown, Green, Grey, Light Greenish Grey, Pink, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Layered, Banded, Veined and Shiny
Layered, Banded, Veined and Shiny
Architecture
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Floor Tiles, Homes, Interior Decoration
Exterior Uses
Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration
Other Architectural Uses
Curbing, Whetstones
Curbing
Industry
Construction Industry
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
As Dimension Stone, Cement Manufacture, for Road Aggregate
Medical Industry
-
-
Antiquity Uses
Artifacts
Artifacts, Sculpture, Small Figurines
Other Uses
Commercial Uses
As a touchstone, Cemetery Markers, Creating Artwork
Creating Artwork, Curling
Types
Algoma-type , Lake Superior-type, Superior-type and Taconite
Proterozoic Anorthosite and Archean Anorthosite
Features
Is one of the oldest rock
Generally rough to touch, Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Present
Absent
Formation
The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
Anorthosite is a phaneritic, intrusive igneous rock which is characterized by a predominance of plagioclase feldspar which is almost 90–100%, and a minimal mafic component.
Composition
Mineral Content
Hematite, Magnetite, Quartz
Amphibole, Clinopyroxene, Ilmenite, Magnetite, Olivine, Orthopyroxene
Compound Content
Fe, Iron(III) Oxide, Silicon Dioxide
Ca, CaO, Chromium(III) Oxide, MgO, Sulfur Trioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
-
Cataclastic Metamorphism, Contact Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Chemical Weathering
Biological Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Wind Erosion
Chemical Erosion, Wind Erosion
Physical Properties
Hardness
5.5-65-6
1
7
👆🏻
Grain Size
Large and Coarse Grained
Coarse Grained
Fracture
Uneven, Splintery or Conchoidal
Irregular
Streak
White
White
Porosity
Highly Porous
Less Porous
Luster
Earthy
Pearly to Subvitreous
Compressive Strength
220.00 N/mm2180.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
1.5
-
Specific Gravity
5.0-5.32.62-2.82
0
8.4
👆🏻
Transparency
Translucent to Opaque
Translucent
Density
-9999 g/cm32.7-4 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
3.20 kJ/Kg K0.84 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
-
Africa
Kenya, Morocco, South Africa, Tanzania
-
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Bulgaria, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Malta, Poland, Portugal, Romania, Slovenia, Spain, Sweden, The Czech Republic
Others
Greenland, Mid-Atlantic Ridge
-
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada
South America
Bolivia, Brazil
Bolivia, Colombia
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
Central Australia, South Australia, Western Australia