Definition
Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
History
Origin
Germany
Western Australia, Minnesota
Discoverer
Van Tooren
Unknown
Etymology
From Greek tephra, ashes from Indo-European base, to burn
From its formation process
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Not Applicable
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Texture
Aphanitic to Porphyritic
Banded, Trellis
Color
Black, Brown, Colourless, Green, Grey, White
Red, Reddish Brown
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
No
Scratch Resistant
Yes
Yes
Stain Resistant
No
Yes
Wind Resistant
Yes
No
Acid Resistant
No
No
Appearance
Vesicular
Layered, Banded, Veined and Shiny
Uses
Architecture
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Paving Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Industry
Construction Industry
Landscaping
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Sculpture
Artifacts
Other Uses
Commercial Uses
Production of Lime, Soil Conditioner
As a touchstone, Cemetery Markers, Creating Artwork
Types
Types
Not Available
Algoma-type , Lake Superior-type, Superior-type and Taconite
Features
Host Rock for Lead
Is one of the oldest rock
Archaeological Significance
Monuments
Not Yet Used
Not Yet Used
Famous Monuments
Not Applicable
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Not Used
Not Used
Petroglyphs
Not Used
Not Used
Figurines
Used
Not Yet Used
Fossils
Absent
Present
Formation
Formation
Tephrite 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.
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.
Composition
Mineral Content
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Hematite, Magnetite, Quartz
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion
Coastal Erosion, Wind Erosion
Properties
Physical Properties
Hardness
6.5
5.5-6
Grain Size
Medium to Fine Coarse Grained
Large and Coarse Grained
Fracture
Uneven
Uneven, Splintery or Conchoidal
Streak
Bluish Black
White
Porosity
Very Less Porous
Highly Porous
Luster
Subvitreous to Dull
Earthy
Compressive Strength
90.00 N/mm2
22
Not Available
Cleavage
Crenulation and Pervasive
Imperfect
Toughness
2.4
1.5
Specific Gravity
2.86
5.0-5.3
Transparency
Opaque
Translucent to Opaque
Density
2.8-2.9 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K
10
3.20 kJ/Kg K
1
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
Not Yet Found
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Namibia, Uganda
Kenya, Morocco, South Africa, Tanzania
Europe
Germany, Hungary, Italy, Portugal, Spain
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Not Yet Found
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
Not Yet Found
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
New South Wales, Queensland, South Australia, Western Australia
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