Tephrite and Mylonite
Definition
Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism
History
Origin
Germany
New Zealand
Discoverer
Van Tooren
Unknown
Etymology
From Greek tephra, ashes from Indo-European base, to burn
From Greek mulōn mill + -ite
Class
Igneous Rocks
Metamorphic 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
Fine Grained Rock, Opaque Rock
Texture
Texture
Aphanitic to Porphyritic
Foliated
Color
Black, Brown, Colourless, Green, Grey, White
Black to Grey
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
No
No
Wind Resistant
Yes
No
Acid Resistant
No
No
Appearance
Vesicular
Dull, Banded and Foilated
Uses
Architecture
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Landscaping
for Road Aggregate, Landscaping, Roadstone
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Sculpture
Artifacts, Monuments
Other Uses
Commercial Uses
Production of Lime, Soil Conditioner
Creating Artwork, Gemstone, Jewelry
Types
Types
Not Available
Blastomylonites, Ultramylonites and Phyllonites
Features
Host Rock for Lead
Surfaces are often shiny
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
Sculpture
Used
Used
Famous Sculptures
Data Not Available
Data Not Available
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Used
Used
Fossils
Absent
Absent
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.
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
Composition
Mineral Content
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Porphyroblasts
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, 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
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Properties
Physical Properties
Hardness
6.5
3-4
Grain Size
Medium to Fine Coarse Grained
Fine Grained
Fracture
Uneven
Conchoidal
Streak
Bluish Black
White
Porosity
Very Less Porous
Highly Porous
Luster
Subvitreous to Dull
Shiny
Compressive Strength
90.00 N/mm2
22
1.28 N/mm2
32
Cleavage
Crenulation and Pervasive
Conchoidal
Toughness
2.4
Not Available
Specific Gravity
2.86
2.97-3.05
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm3
2.6-4.8 g/cm3
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K
10
1.50 kJ/Kg K
3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Reserves
Deposits in Eastern Continents
Asia
Not Yet Found
China, India, Indonesia, Saudi Arabia, South Korea
Africa
Namibia, Uganda
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
Europe
Germany, Hungary, Italy, Portugal, Spain
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
USA
USA
South America
Not Yet Found
Not Yet Found
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
Central Australia, Western Australia
All about Tephrite and Mylonite Properties
Know all about Tephrite and Mylonite properties here. All properties of rocks are important as they define the type of rock and its application. Tephrite belongs to Igneous Rocks while Mylonite belongs to Metamorphic Rocks.Texture of Tephrite is Aphanitic to Porphyritic whereas that of Mylonite is Foliated. Tephrite appears Vesicular and Mylonite appears Dull, Banded and Foilated. The luster of Tephrite is subvitreous to dull while that of Mylonite is shiny. Tephrite is available in black, brown, colourless, green, grey, white colors whereas Mylonite is available in black to grey colors. The commercial uses of Tephrite are production of lime, soil conditioner and that of Mylonite are creating artwork, gemstone, jewelry.
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