Definition
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
History
Origin
Western Australia, Minnesota
Iceland
Discoverer
Johann Gottlob Lehmann
Unknown
Etymology
From its formation process
From German Tachylite, from tachy- + Greek lutos soluble, melting
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Banded, Trellis
Vitreous
Color
Red, Reddish Brown
Black, Dark Brown
Maintenance
Less
More
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Layered, Banded, Veined and Shiny
Glassy
Architecture
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Interior Decoration
Exterior Uses
Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing, Whetstones
Curbing
Industry
Construction Industry
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Cutting Tool, Knives, Landscaping, Scrapers
Medical Industry
-
-
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
As a touchstone, Cemetery Markers, Creating Artwork
Cemetery Markers, Creating Artwork
Types
Algoma-type , Lake Superior-type, Superior-type and Taconite
Volcanic glass
Features
Is one of the oldest rock
Available in Lots of Colors and Patterns, Clasts are smooth to touch
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.
Tachylite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Composition
Mineral Content
Hematite, Magnetite, Quartz
Feldspar, Olivine
Compound Content
Fe, Iron(III) Oxide, Silicon Dioxide
Fe, Mg
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Chemical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Coastal Erosion, Wind Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
5.5-65.5
1
7
👆🏻
Grain Size
Large and Coarse Grained
Medium to Fine Coarse Grained
Fracture
Uneven, Splintery or Conchoidal
Conchoidal
Streak
White
Vermilion
Porosity
Highly Porous
Less Porous
Luster
Earthy
Resinous
Compressive Strength
220.00 N/mm2206.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
1.5
-
Specific Gravity
5.0-5.32.4
0
8.4
👆🏻
Transparency
Translucent to Opaque
Opaque
Density
-9999 g/cm33.058 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
3.20 kJ/Kg K0.56 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Cambodia, Russia, South Korea
Africa
Kenya, Morocco, South Africa, Tanzania
East Africa
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
England, Germany, Hungary, Iceland, Scotland, Sweden
Others
Greenland, Mid-Atlantic Ridge
Hawaii Islands
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Bolivia, Brazil
-
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
Victoria