Definition
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
  
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
England
  
New Zealand
  
Discoverer
Unknown
  
Unknown
  
Etymology
From Old French esclate, from esclat (French éclat)
  
From Greek mulōn mill + -ite
  
Class
Metamorphic Rocks
  
Metamorphic Rocks
  
Sub-Class
Durable Rock, Medium Hardness Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Not Applicable
  
Not Applicable
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Foliated
  
Foliated
  
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
  
Black to Grey
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
Yes
  
No
  
Wind Resistant
No
  
No
  
Acid Resistant
No
  
No
  
Appearance
Dull
  
Dull, Banded and Foilated
  
Architecture
  
  
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
  
Decorative Aggregates, Interior Decoration
  
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
As Dimension Stone
  
for Road Aggregate, Landscaping, Roadstone
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Monuments
  
Other Uses
  
  
Commercial Uses
Blackboards, Commemorative Tablets, Laboratory bench tops, Standard material for the bed of Billiard table, Standard material for the beds of Pool and Snooker table, Tombstones, Used in aquariums, Writing Slates
  
Creating Artwork, Gemstone, Jewelry
  
Types
Not Available
  
Blastomylonites, Ultramylonites and Phyllonites
  
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
  
Surfaces are often shiny
  
Archaeological Significance
  
  
Monuments
Used
  
Used
  
Famous Monuments
Data Not Available
  
Data Not Available
  
Sculpture
Used
  
Used
  
Famous Sculptures
Data Not Available
  
Data Not Available
  
Pictographs
Used
  
Used
  
Petroglyphs
Used
  
Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Absent
  
Formation
Slate is a low grade metamorphic rock that is generally formed by metamorphosis of mudstone or shale, under relatively low pressure and temperature conditions.
  
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
  
Composition
  
  
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
  
Porphyroblasts
  
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
No
  
Types of Metamorphism
Burial Metamorphism, Cataclastic 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
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Sea Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
3-4
  
3-4
  
Grain Size
Very fine-grained
  
Fine Grained
  
Fracture
Splintery
  
Conchoidal
  
Streak
Light to dark brown
  
White
  
Porosity
Less Porous
  
Highly Porous
  
Luster
Dull
  
Shiny
  
Compressive Strength
30.00 N/mm2
  
30
Cleavage
Slaty
  
Conchoidal
  
Toughness
1.2
  
Not Available
  
Specific Gravity
2.65-2.8
  
2.97-3.05
  
Transparency
Opaque
  
Opaque
  
Density
2.6-2.8 g/cm3
  
2.6-4.8 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.76 kJ/Kg K
  
17
1.50 kJ/Kg K
  
3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant
  
Deposits in Eastern Continents
  
  
Asia
China, India, Turkey
  
China, India, Indonesia, Saudi Arabia, South Korea
  
Africa
Not Yet Found
  
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
  
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
  
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
  
Others
Arctic
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
USA
  
USA
  
South America
Brazil
  
Not Yet Found
  
Deposits in Oceania Continent
  
  
Australia
Not Yet Found
  
Central Australia, Western Australia