Definition
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
Blueschist is a metamorphic rock which is generally blue in color and is formed under conditions of high pressure and low temperature
History
Origin
USA
USA
Discoverer
Unknown
Edgar Bailey
Etymology
From pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
From French schiste, Greek skhistos i.e. split
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
-
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Quench
Foliated
Color
Black, Brown, Green, Grey, Pink, White
Blue, Bluish - Grey, Purple, Shades of Blue
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull and Soft
Dull and Banded
Architecture
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration
Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
-
Industry
Construction Industry
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Gemstone
Cemetery Markers, Commemorative Tablets, Creating Artwork, Curling, Tombstones
Types
Cataclastic rock
Metamorphic rock
Features
Host Rock for Lead
Has High structural resistance against erosion and climate, Very fine grained rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
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.
Blueschist forms due to the metamorphism of basalt and other rocks with similar composition at high pressures and low temperatures and approximately corresponding to a depth of 15 to 30 kilometers and 200 to 500 °C.
Composition
Mineral Content
Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides
Albite, Chlorite, Epidote, Garnet, Glaucophane, Lawsonite, Muscovite or Illite, Quartz
Compound Content
Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
-
Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
-
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
73.5-4
1
7
👆🏻
Grain Size
Very fine-grained
Fine to Medium Grained
Fracture
Uneven
Conchoidal
Streak
Light to dark brown
White to Grey
Porosity
Less Porous
Highly Porous
Luster
Vitreous
Dull
Compressive Strength
60.00 N/mm2220.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Slaty
Toughness
-
1.5
Specific Gravity
2.46-2.863-3.2
0
8.4
👆🏻
Transparency
Transparent to Translucent
Opaque
Density
2.7-2.9 g/cm32.8-2.9 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K0.84 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant
Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
South Korea
Japan, Turkey
Africa
Western Africa
Egypt, Ethiopia, South Africa
Europe
Great Britain, Switzerland
France, Greece, Iceland
Others
-
-
Deposits in Western Continents
North America
-
USA
South America
-
-
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New Zealand