Skarn and Porphyry
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
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
History
Origin
USA, Australia
Egypt
Discoverer
Tornebohm
Unknown
Etymology
From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Earthy, Mud-rich, Rough
Porphyritic
Color
Black, Brown, Colourless, Green, Grey, White
Black, Brown, Colourless, Green, Grey, Red, Rust, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
No
Scratch Resistant
Yes
Yes
Stain Resistant
No
Yes
Wind Resistant
Yes
No
Acid Resistant
Yes
Yes
Appearance
Dull
Dull
Uses
Architecture
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Garden Decoration, Paving Stone
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
Construction Aggregate
Medical Industry
Not Applicable
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)
Creating Artwork, Gemstone, Jewelry
Types
Types
Endoskarns
Rhomb Porphyry
Features
Host Rock for Lead, Zinc and Copper Deposits
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
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
Not Used
Petroglyphs
Not Used
Not Used
Figurines
Used
Used
Fossils
Absent
Absent
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.
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
Composition
Mineral Content
Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Compound Content
Au, CaO, Carbon Dioxide, Cu, Fe, MgO
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
No
Yes
Types of Weathering
Not Applicable
Biological Weathering, Chemical Weathering, Not Registered
Erosion
No
Yes
Types of Erosion
Not Applicable
Chemical Erosion, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
6.5
6-7
Grain Size
Fine Grained
Fine Grained
Fracture
Irregular
Irregular
Streak
Light to dark brown
White
Porosity
Less Porous
Less Porous
Luster
Waxy and Dull
Dull
Cleavage
Slaty
Imperfect
Toughness
2.4
1.7
Specific Gravity
2.86
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
2.8-2.9 g/cm3
2.5-2.52 g/cm3
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K
10
Not Available
Resistance
Heat Resistant
Heat Resistant, Impact Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Russia, Saudi Arabia, South Korea, Sri Lanka
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
South Africa, Western Africa
Egypt, Ethiopia, Ghana, South Africa
Europe
United Kingdom
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Others
Not Yet Found
Greenland
Deposits in Western Continents
North America
Canada
Canada, Cuba, Jamaica, USA
South America
Brazil, Colombia, Paraguay
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New South Wales, New Zealand, Western Australia
All about Skarn and Porphyry Properties
Know all about Skarn and Porphyry properties here. All properties of rocks are important as they define the type of rock and its application. Skarn belongs to Metamorphic Rocks while Porphyry belongs to Igneous Rocks.Texture of Skarn is Earthy, Mud-rich, Rough whereas that of Porphyry is Porphyritic. Skarn appears Dull and Porphyry appears Dull. The luster of Skarn is waxy and dull while that of Porphyry is dull. Skarn is available in black, brown, colourless, green, grey, white colors whereas Porphyry is available in black, brown, colourless, green, grey, red, rust, white colors. The commercial uses of Skarn and Porphyry are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).
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