Skarn and Coquina
Definition
Definition
Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin
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
USA, Australia
European Foreland Basins
Discoverer
Tornebohm
Unknown
Etymology
From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard 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
Earthy, Mud-rich, Rough
Clastic
Color
Black, Brown, Colourless, Green, Grey, White
Beige, Buff, Orange
Maintenance
Less
More
Durability
Durable
Non-Durable
Water Resistant
Yes
No
Scratch Resistant
Yes
No
Stain Resistant
No
No
Wind Resistant
Yes
No
Acid Resistant
Yes
No
Appearance
Dull
Layered, Banded, Veined and Shiny
Uses
Architecture
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Decorative Aggregates, Homes, Hotels, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
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
Building houses or walls, Construction Aggregate
Medical Industry
Not Applicable
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments, Sculpture, Small Figurines
Other Uses
Commercial Uses
Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)
Creating Artwork
Types
Types
Endoskarns
Not Available
Features
Host Rock for Lead, Zinc and Copper Deposits
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
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Used
Used
Fossils
Absent
Present
Formation
Formation
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.
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
Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite
Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite
Compound Content
Au, CaO, Carbon Dioxide, Cu, Fe, MgO
CaO, Carbon Dioxide, Iron(III) Oxide, MgO
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
Weathering
No
Yes
Types of Weathering
Not Applicable
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
No
Yes
Types of Erosion
Not Applicable
Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion
Properties
Physical Properties
Hardness
6.5
1-2
Grain Size
Fine Grained
Coarse Grained
Fracture
Irregular
Irregular
Streak
Light to dark brown
White
Porosity
Less Porous
Highly Porous
Luster
Waxy and Dull
Dull to Vitreous to Submetallic
Cleavage
Slaty
Not Available
Toughness
2.4
Not Available
Specific Gravity
2.86
1.10-2.24
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm3
2.8-2.9 g/cm3
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K
10
Not Available
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Russia, Saudi Arabia, South Korea, Sri Lanka
Not Yet Found
Africa
South Africa, Western Africa
Not Yet Found
Europe
United Kingdom
United Kingdom
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada
USA
South America
Brazil, Colombia, Paraguay
Not Yet Found
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
Not Yet Found
All about Skarn and Coquina Properties
Know all about Skarn and Coquina properties here. All properties of rocks are important as they define the type of rock and its application. Skarn belongs to Metamorphic Rocks while Coquina belongs to Sedimentary Rocks.Texture of Skarn is Earthy, Mud-rich, Rough whereas that of Coquina is Clastic. Skarn appears Dull and Coquina appears Layered, Banded, Veined and Shiny. The luster of Skarn is waxy and dull while that of Coquina is dull to vitreous to submetallic. Skarn is available in black, brown, colourless, green, grey, white colors whereas Coquina is available in beige, buff, orange colors. The commercial uses of Skarn and Coquina are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).
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