Argillite and Coquina
Definition
Definition
Argillites are highly compact sedimentary or slightly metamorphosed rocks that consist largely or wholly of particles of clay or silt but lack the fissility of shale or the cleavage characteristic of slate
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
History
Origin
Unknown
European Foreland Basins
Discoverer
Unknown
Unknown
Etymology
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Soft Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Texture
Clastic, Polished
Clastic
Color
Dark Grey to Black, Pink, Red, White
Beige, Buff, Orange
Maintenance
Less
More
Durability
Durable
Non-Durable
Water Resistant
No
No
Scratch Resistant
Yes
No
Stain Resistant
Yes
No
Wind Resistant
Yes
No
Acid Resistant
Yes
No
Appearance
Rough and Dull
Layered, Banded, Veined and Shiny
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Homes, Hotels, Interior Decoration
Exterior Uses
As Building Stone, Garden Decoration, Office Buildings
Garden Decoration, Office Buildings
Other Architectural Uses
Curbing, Whetstones
Curbing
Industry
Construction Industry
Used for flooring, stair treads, borders and window sills.
Building houses or walls, Construction Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments, Sculpture, Small Figurines
Other Uses
Commercial Uses
Fire resistant, Used to manufracture paperweights and bookends
Creating Artwork
Types
Types
Not Available
Not Available
Features
Is one of the oldest rock
Available in Lots of Colors and Patterns, Is one of the oldest rock
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Used
Used
Famous Sculptures
Data Not Available
Data Not Available
Pictographs
Used
Used
Petroglyphs
Used
Used
Figurines
Used
Used
Fossils
Present
Present
Formation
Formation
An argillite is a fine-grained sedimentary rock mainly composed of clay particles which forms from lithified muds which contain variable amounts of silt-sized particles.
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.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite
Compound Content
Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide
CaO, Carbon Dioxide, Iron(III) Oxide, MgO
Transformation
Metamorphism
No
No
Types of Metamorphism
Not Applicable
Not Applicable
Weathering
Yes
Yes
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion
Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion
Properties
Physical Properties
Hardness
2-3
1-2
Grain Size
Fine Grained
Coarse Grained
Fracture
Conchoidal to Uneven
Irregular
Streak
White to Grey
White
Porosity
Highly Porous
Highly Porous
Luster
Waxy and Dull
Dull to Vitreous to Submetallic
Cleavage
Slaty
Not Available
Toughness
2.6
Not Available
Specific Gravity
2.56-2.68
1.10-2.24
Transparency
Opaque
Opaque
Density
2.54-2.66 g/cm3
2.8-2.9 g/cm3
Thermal Properties
Specific Heat Capacity
0.87 kJ/Kg K
14
Not Available
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
Bangladesh, China, India, Russia
Not Yet Found
Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Not Yet Found
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
United Kingdom
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
USA
USA
South America
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Not Yet Found
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia
Not Yet Found
All about Argillite and Coquina Properties
Know all about Argillite and Coquina properties here. All properties of rocks are important as they define the type of rock and its application. Argillite and Coquina belong to Sedimentary Rocks.Texture of Argillite is Clastic, Polished whereas that of Coquina is Clastic. Argillite appears Rough and Dull and Coquina appears Layered, Banded, Veined and Shiny. The luster of Argillite is waxy and dull while that of Coquina is dull to vitreous to submetallic. Argillite is available in dark grey to black, pink, red, white colors whereas Coquina is available in beige, buff, orange colors. The commercial uses of Argillite are fire resistant, used to manufracture paperweights and bookends and that of Coquina are creating artwork.
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