Chert and Skarn
Definition
Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin
History
Origin
Unknown
USA, Australia
Discoverer
Unknown
Tornebohm
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Banded, Rough
Earthy, Mud-rich, Rough
Color
Black, Brown, Green, Grey, Red, White
Black, Brown, Colourless, Green, Grey, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
No
Wind Resistant
No
Yes
Acid Resistant
Yes
Yes
Appearance
Glassy or Pearly
Dull
Uses
Architecture
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, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
As a Flux in the Production of Steel and Pig Iron, As a Sintering Agent in Steel Industry to process Iron Ore, As Dimension Stone, Gold and Silver production, Manufacture of Magnesium and Dolomite Refractories
Medical Industry
Not Yet Used
Not Applicable
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)
Types
Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Endoskarns
Features
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Host Rock for Lead, Zinc and Copper Deposits
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Not Used
Not Used
Petroglyphs
Not Used
Not Used
Figurines
Not Yet Used
Used
Fossils
Present
Absent
Formation
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. Skarn is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Composition
Mineral Content
Quartz, Silicon
Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite
Compound Content
Silicon Dioxide
Au, CaO, Carbon Dioxide, Cu, Fe, MgO
Transformation
Metamorphism
No
Yes
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
No
No
Types of Weathering
Not Applicable
Not Applicable
Erosion
Yes
No
Types of Erosion
Chemical Erosion
Not Applicable
Properties
Physical Properties
Hardness
6.5-7
6.5
Grain Size
Very fine-grained
Fine Grained
Fracture
Uneven, Splintery or Conchoidal
Irregular
Streak
White
Light to dark brown
Porosity
Highly Porous
Less Porous
Luster
Waxy and Dull
Waxy and Dull
Compressive Strength
450.00 N/mm2
1
Not Available
Cleavage
Non-Existent
Slaty
Toughness
1.5
2.4
Specific Gravity
2.5-2.8
2.86
Transparency
Translucent to Opaque
Opaque
Density
2.7 g/cm3
2.8-2.9 g/cm3
Thermal Properties
Specific Heat Capacity
0.74 kJ/Kg K
19
0.92 kJ/Kg K
10
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
China, India, Russia, Saudi Arabia, South Korea, Sri Lanka
Africa
Kenya, Morocco, South Africa, Tanzania
South Africa, Western Africa
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
United Kingdom
Others
Greenland, Mid-Atlantic Ridge
Not Yet Found
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada
South America
Bolivia, Brazil
Brazil, Colombia, Paraguay
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
Central Australia, Western Australia
All about Chert and Skarn Properties
Know all about Chert and Skarn properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Skarn belongs to Metamorphic Rocks.Texture of Chert is Banded, Rough whereas that of Skarn is Earthy, Mud-rich, Rough. Chert appears Glassy or Pearly and Skarn appears Dull. The luster of Chert and Skarn is waxy and dull. Chert is available in black, brown, green, grey, red, white colors whereas Skarn is available in black, brown, colourless, green, grey, white colors. The commercial uses of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms and that of Skarn are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).
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