Definition
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Argillites are highly compact sedimentary or slightly metamorphosed rocks that consist largely or wholly of particles of clay or silt but lack the fissility of shale or the cleavage characteristic of slate
History
Origin
Western Australia, Minnesota
-
Discoverer
Johann Gottlob Lehmann
Unknown
Etymology
From its formation process
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
-
-
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Banded, Trellis
Clastic, Polished
Color
Red, Reddish Brown
Dark Grey to Black, Pink, Red, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Layered, Banded, Veined and Shiny
Rough and Dull
Architecture
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
Paving Stone, Office Buildings
As Building Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing, Whetstones
Curbing, Whetstones
Industry
Construction Industry
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Used for flooring, stair treads, borders and window sills.
Medical Industry
-
-
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
As a touchstone, Cemetery Markers, Creating Artwork
Fire resistant, Used to manufracture paperweights and bookends
Types
Algoma-type , Lake Superior-type, Superior-type and Taconite
Metamorphic rock
Features
Is one of the oldest rock
Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Present
Present
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.
An argillite is a fine-grained sedimentary rock mainly composed of clay particles which forms from lithified muds which contain variable amounts of silt-sized particles.
Composition
Mineral Content
Hematite, Magnetite, Quartz
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Compound Content
Fe, Iron(III) Oxide, Silicon Dioxide
Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
-
-
Weathering
✔
✘
✔
✘
Types of Weathering
Chemical Weathering
Biological Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Wind Erosion
Chemical Erosion
Physical Properties
Hardness
5.5-62-3
1
7
👆🏻
Grain Size
Large and Coarse Grained
Fine Grained
Fracture
Uneven, Splintery or Conchoidal
Conchoidal to Uneven
Streak
White
White to Grey
Porosity
Highly Porous
Highly Porous
Luster
Earthy
Waxy and Dull
Compressive Strength
220.00 N/mm2-
0.15
450
👆🏻
Cleavage
-
Slaty
Toughness
1.5
2.6
Specific Gravity
5.0-5.32.56-2.68
0
8.4
👆🏻
Transparency
Translucent to Opaque
Opaque
Density
-9999 g/cm32.54-2.66 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
3.20 kJ/Kg K0.87 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Bangladesh, China, India, Russia
Africa
Kenya, Morocco, South Africa, Tanzania
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
Greenland, Mid-Atlantic Ridge
-
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Bolivia, Brazil
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia