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
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
Origin
New Zealand
Romania and Moldova, Europe
Discoverer
Unknown
Unknown
Etymology
From Greek mulōn mill + -ite
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Group
Not Applicable
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Foliated
Aphanitic to Porphyritic
Color
Black to Grey
Bluish - Grey, Brown, Grey, Light to Dark Grey
Durability
Durable
Durable
Appearance
Dull, Banded and Foilated
Vesicular
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, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Landscaping, Roadstone
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments
Artifacts
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Commemorative Tablets, Creating Artwork
Types
Blastomylonites, Ultramylonites and Phyllonites
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Surfaces are often shiny
Host Rock for Lead, Is one of the oldest rock
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Data Not Available
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Figurines
Used
Not Yet Used
Formation
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
Mineral Content
Porphyroblasts
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Chemical Erosion
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Porosity
Highly Porous
Less Porous
Luster
Shiny
Subvitreous to Dull
Compressive Strength
Not Available
Cleavage
Conchoidal
Perfect
Toughness
Not Available
Not Available
Specific Gravity
2.97-3.05
2.86-2.87
Transparency
Opaque
Translucent
Density
2.6-4.8 g/cm3
2.77-2.771 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Indonesia, Saudi Arabia, South Korea
Not Yet Found
Africa
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
Not Yet Found
Europe
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
France, Greece, Romania, Scotland, Spain
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
South America
Not Yet Found
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New Zealand, South Australia, Western Australia