Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
Discoverer
Unknown
Unknown
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
From pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Banded, Rough
Quench
Color
Black, Brown, Green, Grey, Red, White
Black, Brown, Green, Grey, Pink, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Glassy or Pearly
Dull and Soft
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Construction Industry
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments
Commercial Uses
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Creating Artwork, Gemstone
Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Cataclastic rock
Features
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Host Rock for Lead
Archaeological Significance
Formation
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.
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
Quartz, Silicon
Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides
Compound Content
Silicon Dioxide
Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Types of Erosion
Chemical Erosion
-
Grain Size
Very fine-grained
Very fine-grained
Fracture
Uneven, Splintery or Conchoidal
Uneven
Streak
White
Light to dark brown
Porosity
Highly Porous
Less Porous
Luster
Waxy and Dull
Vitreous
Specific Gravity
2.5-2.8
2.46-2.86
Transparency
Translucent to Opaque
Transparent to Translucent
Density
2.7 g/cm3
2.7-2.9 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
South Korea
Africa
Kenya, Morocco, South Africa, Tanzania
Western Africa
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Great Britain, Switzerland
Others
Greenland, Mid-Atlantic Ridge
-
Deposits in Western Continents
North America
Canada, Mexico, USA
-
South America
Bolivia, Brazil
-
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
Central Australia, Western Australia
All about Chert and Pseudotachylite Properties
Know all about Chert and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Pseudotachylite belongs to Metamorphic Rocks.Texture of Chert is Banded, Rough whereas that of Pseudotachylite is Quench. Chert appears Glassy or Pearly and Pseudotachylite appears Dull and Soft. The luster of Chert is waxy and dull while that of Pseudotachylite is vitreous. Chert is available in black, brown, green, grey, red, white colors whereas Pseudotachylite is available in black, brown, green, grey, pink, white colors. The commercial uses of Chert and Pseudotachylite are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.