Chert and Foidolite
Definition
Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Foidolite is a rare type of coarse-grained intrusive igneous rock with a feldspathoid mineral content greater than 60%
History
Discoverer
Unknown
Unknown
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
From the mineral feldspathoid which is the main content of rock
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
Not Applicable
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Banded, Rough
Earthy
Color
Black, Brown, Green, Grey, Red, White
Black, Brown, Colourless, Green, Grey, Pink, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
No
Scratch Resistant
Yes
No
Stain Resistant
Yes
No
Wind Resistant
No
No
Acid Resistant
Yes
No
Appearance
Glassy or Pearly
Dull
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, 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 Dimension Stone, Cement Manufacture, for Road Aggregate
Medical Industry
Not Yet Used
Taken as a Supplement for Calcium or Magnesium
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
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Not Available
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
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
Used
Petroglyphs
Not Used
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.
Foidolites is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Composition
Mineral Content
Quartz, Silicon
Amphibole, Biotite, Feldspar, Olivine, Plagioclase, Pyroxene
Compound Content
Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO
Transformation
Metamorphism
No
Yes
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Impact 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
1.5
Grain Size
Very fine-grained
Medium to Fine Coarse Grained
Fracture
Uneven, Splintery or Conchoidal
Conchoidal
Streak
White
White
Porosity
Highly Porous
Very Less Porous
Luster
Waxy and Dull
Subvitreous to Dull
Compressive Strength
450.00 N/mm2
1
Not Available
Cleavage
Non-Existent
Perfect
Toughness
1.5
Not Available
Specific Gravity
2.5-2.8
2.86
Transparency
Translucent to Opaque
Translucent
Density
2.7 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
0.74 kJ/Kg K
19
Not Available
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Russia
Africa
Kenya, Morocco, South Africa, Tanzania
South Africa, Western Africa
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Not Yet Found
Others
Greenland, Mid-Atlantic Ridge
Not Yet Found
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Bolivia, Brazil
Not Yet Found
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
Central Australia, Western Australia
All about Chert and Foidolite Properties
Know all about Chert and Foidolite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Foidolite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Foidolite is Earthy. Chert appears Glassy or Pearly and Foidolite appears Dull. The luster of Chert is waxy and dull while that of Foidolite is subvitreous to dull. Chert is available in black, brown, green, grey, red, white colors whereas Foidolite is available in black, brown, colourless, green, grey, pink, 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 Foidolite are cemetery markers, commemorative tablets, creating artwork.
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