Definition
Blueschist is a metamorphic rock which is generally blue in color and is formed under conditions of high pressure and low temperature
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Discoverer
Edgar Bailey
Unknown
Etymology
From French schiste, Greek skhistos i.e. split
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Foliated
Banded, Rough
Color
Blue, Bluish - Grey, Purple, Shades of Blue
Black, Brown, Green, Grey, Red, White
Durability
Durable
Durable
Appearance
Dull and Banded
Glassy or Pearly
Interior Uses
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Decorative Aggregates, Homes
Exterior Uses
Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
-
Curbing
Construction Industry
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork, Curling, Tombstones
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Metamorphic rock
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Has High structural resistance against erosion and climate, Very fine grained rock
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Formation
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.
Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.
Mineral Content
Albite, Chlorite, Epidote, Garnet, Glaucophane, Lawsonite, Muscovite or Illite, Quartz
Quartz, Silicon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Silicon Dioxide
Types of Metamorphism
-
-
Types of Weathering
Mechanical Weathering
-
Types of Erosion
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Chemical Erosion
Grain Size
Fine to Medium Grained
Very fine-grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Streak
White to Grey
White
Porosity
Highly Porous
Highly Porous
Luster
Dull
Waxy and Dull
Specific Gravity
3-3.2
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
2.8-2.9 g/cm3
2.7 g/cm3
Resistance
Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Japan, Turkey
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Egypt, Ethiopia, South Africa
Kenya, Morocco, South Africa, Tanzania
Europe
France, Greece, Iceland
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
-
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
-
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, Queensland, South Australia, Western Australia
All about Blueschist and Chert Properties
Know all about Blueschist and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Blueschist belongs to Metamorphic Rocks while Chert belongs to Sedimentary Rocks.Texture of Blueschist is Foliated whereas that of Chert is Banded, Rough. Blueschist appears Dull and Banded and Chert appears Glassy or Pearly. The luster of Blueschist is dull while that of Chert is waxy and dull. Blueschist is available in blue, bluish - grey, purple, shades of blue colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Blueschist are cemetery markers, commemorative tablets, creating artwork, curling, tombstones and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.