Coquina and Chert
Definition
Definition
Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
History
Origin
European Foreland Basins
Unknown
Discoverer
Unknown
Unknown
Etymology
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Clastic
Banded, Rough
Color
Beige, Buff, Orange
Black, Brown, Green, Grey, Red, White
Maintenance
More
Less
Durability
Non-Durable
Durable
Water Resistant
No
Yes
Scratch Resistant
No
Yes
Stain Resistant
No
Yes
Wind Resistant
No
No
Acid Resistant
No
Yes
Appearance
Layered, Banded, Veined and Shiny
Glassy or Pearly
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Building houses or walls, Construction Aggregate
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
Other Uses
Commercial Uses
Creating Artwork
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Types
Not Available
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Available in Lots of Colors and Patterns, Is one of the oldest rock
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Not Yet Used
Fossils
Present
Present
Formation
Formation
Coquina is a sedimentary rock which is formed when billions of small clam-like seashell, called Coquina, or cockleshell are die and hence are deposited, buried and turns into a rock when pressure is applied.
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.
Composition
Mineral Content
Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite
Quartz, Silicon
Compound Content
CaO, Carbon Dioxide, Iron(III) Oxide, MgO
Silicon Dioxide
Transformation
Metamorphism
No
No
Types of Metamorphism
Not Applicable
Not Applicable
Weathering
Yes
No
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Not Applicable
Erosion
Yes
Yes
Types of Erosion
Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion
Properties
Physical Properties
Hardness
1-2
6.5-7
Grain Size
Coarse Grained
Very fine-grained
Fracture
Irregular
Uneven, Splintery or Conchoidal
Streak
White
White
Porosity
Highly Porous
Highly Porous
Luster
Dull to Vitreous to Submetallic
Waxy and Dull
Compressive Strength
Not Available
450.00 N/mm2
1
Cleavage
Not Available
Non-Existent
Toughness
Not Available
1.5
Specific Gravity
1.10-2.24
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
2.8-2.9 g/cm3
2.7 g/cm3
Thermal Properties
Specific Heat Capacity
Not Available
0.74 kJ/Kg K
19
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
Not Yet Found
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Not Yet Found
Kenya, Morocco, South Africa, Tanzania
Europe
United Kingdom
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Not Yet Found
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
Not Yet Found
Bolivia, Brazil
Deposits in Oceania Continent
Australia
Not Yet Found
New South Wales, Queensland, South Australia, Western Australia
All about Coquina and Chert Properties
Know all about Coquina and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Coquina and Chert belong to Sedimentary Rocks.Texture of Coquina is Clastic whereas that of Chert is Banded, Rough. Coquina appears Layered, Banded, Veined and Shiny and Chert appears Glassy or Pearly. The luster of Coquina is dull to vitreous to submetallic while that of Chert is waxy and dull. Coquina is available in beige, buff, orange colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Coquina are creating artwork and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.
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