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Chert and Comendite


Comendite and Chert


Definition

Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture   
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite   

History
  
  

Origin
Unknown   
Italy   

Discoverer
Unknown   
Unknown   

Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use   
Comendite derives its name from the area of Le Commende on San Pietro Island in Italy   

Class
Sedimentary Rocks   
Igneous Rocks   

Sub-Class
Durable Rock, Hard Rock   
Durable Rock, Hard Rock   

Family
  
  

Group
Not Applicable   
Volcanic   

Other Categories
Fine Grained Rock, Opaque Rock   
Medium Grained Rock, Opaque Rock   

Texture

Texture
Banded, Rough   
Porphyritic   

Color
Black, Brown, Green, Grey, Red, White   
Blue, Bluish - Grey   

Maintenance
Less   
Less   

Durability
Durable   
Durable   

Water Resistant
Yes   
Yes   

Scratch Resistant
Yes   
Yes   

Stain Resistant
Yes   
Yes   

Wind Resistant
No   
Yes   

Acid Resistant
Yes   
Yes   

Appearance
Glassy or Pearly   
Foliated   

Uses

Architecture
  
  

Interior Uses
Decorative Aggregates, Homes   
Countertops, Decorative Aggregates, 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   

Industry
  
  

Construction Industry
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points   
Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Raw material for the manufacture of mortar   

Medical Industry
Not Yet Used   
Not Yet Used   

Antiquity Uses
Artifacts, Monuments   
Artifacts   

Other Uses
  
  

Commercial Uses
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms   
Cemetery Markers   

Types

Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter   
Rhyolite   

Features
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate   
Very fine grained rock, It is One of the Oldest, Strongest and Hardest Rock   

Archaeological Significance
  
  

Monuments
Used   
Not Yet Used   

Famous Monuments
Data Not Available   
Not Applicable   

Sculpture
Not Yet Used   
Not Yet Used   

Famous Sculptures
Not Applicable   
Not Applicable   

Pictographs
Not Used   
Not Used   

Petroglyphs
Not Used   
Not Used   

Figurines
Not Yet Used   
Not Yet 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.   
Comendite is a type of Igneous rock which is formed due to cooling and solidification of lava or magma. It may form with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.   

Composition
  
  

Mineral Content
Quartz, Silicon   
Albite, Amphibole, Quartz   

Compound Content
Silicon Dioxide   
Al, Fe, Potassium Oxide   

Transformation
  
  

Metamorphism
No   
Yes   

Types of Metamorphism
Not Applicable   
Cataclastic Metamorphism, Regional Metamorphism   

Weathering
No   
Yes   

Types of Weathering
Not Applicable   
Biological Weathering, Chemical Weathering, Mechanical Weathering   

Erosion
Yes   
Yes   

Types of Erosion
Chemical Erosion   
Coastal Erosion, Water Erosion   

Properties

Physical Properties
  
  

Hardness
6.5-7   
6-7   

Grain Size
Very fine-grained   
Medium Grained   

Fracture
Uneven, Splintery or Conchoidal   
Pervasive   

Streak
White   
Bluish Black   

Porosity
Highly Porous   
Highly Porous   

Luster
Waxy and Dull   
Dull   

Compressive Strength
450.00 N/mm2   
1
92.40 N/mm2   
21

Cleavage
Non-Existent   
Not Available   

Toughness
1.5   
2   

Specific Gravity
2.5-2.8   
2.38   

Transparency
Translucent to Opaque   
Opaque   

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, Impact Resistant   

Reserves

Deposits in Eastern Continents
  
  

Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam   
China   

Africa
Kenya, Morocco, South Africa, Tanzania   
East Africa   

Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom   
Italy   

Others
Greenland, Mid-Atlantic Ridge   
Not Yet Found   

Deposits in Western Continents
  
  

North America
Canada, Mexico, USA   
Not Yet Found   

South America
Bolivia, Brazil   
Not Yet Found   

Deposits in Oceania Continent
  
  

Australia
New South Wales, Queensland, South Australia, Western Australia   
Queensland   

Summary >>
<< Reserves

All about Chert and Comendite Properties

Know all about Chert and Comendite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Comendite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Comendite is Porphyritic. Chert appears Glassy or Pearly and Comendite appears Foliated. The luster of Chert is waxy and dull while that of Comendite is dull. Chert is available in black, brown, green, grey, red, white colors whereas Comendite is available in blue, bluish - grey 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 Comendite are cemetery markers.

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