Definition
Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
Discoverer
Unknown
Unknown
Etymology
From Greek mulōn mill + -ite
From pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Color
Black to Grey
Black, Brown, Colourless, Green, Grey, Pink, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull, Banded and Foilated
Dull and Soft
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Landscaping, Roadstone
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Creating Artwork, Gemstone
Types
Blastomylonites, Ultramylonites and Phyllonites
Not Available
Features
Surfaces are often shiny
Host Rock for Lead
Archaeological Significance
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Not Yet Used
Formation
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Mineral Content
Porphyroblasts
Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides
Compound Content
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide
Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Not Applicable
Types of Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Not Applicable
Grain Size
Fine Grained
Very fine-grained
Fracture
Conchoidal
Uneven
Streak
White
Light to dark brown
Porosity
Highly Porous
Less Porous
Cleavage
Conchoidal
Irregular
Toughness
Not Available
Not Available
Specific Gravity
2.97-3.05
2.46-2.86
Transparency
Opaque
Transparent to Translucent
Density
2.6-4.8 g/cm3
2.7-2.9 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, India, Indonesia, Saudi Arabia, South Korea
South Korea
Africa
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
Western Africa
Europe
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
Great Britain, Switzerland
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
USA
Not Yet Found
South America
Not Yet Found
Not Yet Found
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
Central Australia, Western Australia
All about Mylonite and Pseudotachylite Properties
Know all about Mylonite and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Mylonite and Pseudotachylite belong to Metamorphic Rocks.Texture of Mylonite is Foliated whereas that of Pseudotachylite is Quench. Mylonite appears Dull, Banded and Foilated and Pseudotachylite appears Dull and Soft. The luster of Mylonite is shiny while that of Pseudotachylite is vitreous. Mylonite is available in black to grey colors whereas Pseudotachylite is available in black, brown, colourless, green, grey, pink, white colors. The commercial uses of Mylonite and Pseudotachylite are creating artwork, gemstone, jewelry.