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
  
Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
  
History
  
  
Origin
USA, Australia
  
Unknown
  
Discoverer
Tornebohm
  
Unknown
  
Etymology
From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.
  
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
  
Class
Metamorphic Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Hard Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Not Applicable
  
Volcanic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Earthy, Mud-rich, Rough
  
Vesicular
  
Color
Black, Brown, Colourless, Green, Grey, White
  
Black, Brown, Dark Grey to Black, Red
  
Maintenance
Less
  
More
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
No
  
No
  
Wind Resistant
Yes
  
No
  
Acid Resistant
Yes
  
No
  
Appearance
Dull
  
Glassy and Vesicular
  
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
  
Cement Manufacture, Construction Aggregate, for Road Aggregate, In landscaping and drainage works
  
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)
  
As a traction material on snow-covered roads, Creating Artwork, High-temperature insulation, In gas barbecue grills
  
Types
Endoskarns
  
Not Available
  
Features
Host Rock for Lead, Zinc and Copper Deposits
  
Available in Lots of Colors and Patterns, Generally rough to touch, 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
  
Used
  
Petroglyphs
Not Used
  
Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Absent
  
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.
  
Scoria forms when magma containing huge amount of dissolved gas flows from a volcano during an eruption.
  
Composition
  
  
Mineral Content
Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite
  
Apatite, Biotite, Calcite, Feldspar, Hematite, Hornblade, Ilmenite, Magnetite, Olivine, Pyroxene, Quartz, Silica
  
Compound Content
Au, CaO, Carbon Dioxide, Cu, Fe, MgO
  
Ca, NaCl
  
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
  
Weathering
No
  
Yes
  
Types of Weathering
Not Applicable
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
No
  
Yes
  
Types of Erosion
Not Applicable
  
Chemical Erosion, Coastal Erosion, Glacier Erosion
  
Physical Properties
  
  
Hardness
6.5
  
5-6
  
Grain Size
Fine Grained
  
Fine Grained
  
Fracture
Irregular
  
Conchoidal
  
Streak
Light to dark brown
  
White
  
Porosity
Less Porous
  
Highly Porous
  
Luster
Waxy and Dull
  
Subvitreous to Dull
  
Cleavage
Slaty
  
Perfect
  
Toughness
2.4
  
2.1
  
Specific Gravity
2.86
  
Not Available
  
Transparency
Opaque
  
Opaque
  
Density
2.8-2.9 g/cm3
  
Not Available
  
Thermal Properties
  
  
Specific Heat Capacity
0.92 kJ/Kg K
  
10
Not Available
  
Resistance
Heat Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
China, India, Russia, Saudi Arabia, South Korea, Sri Lanka
  
Afghanistan, Indonesia, Japan, Russia
  
Africa
South Africa, Western Africa
  
Ethiopia, Kenya, Tanzania
  
Europe
United Kingdom
  
Greece, Hungary, Iceland, Italy, Turkey
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada
  
Bahamas, Barbados, Canada, Costa Rica, Cuba, Jamaica, Mexico, USA
  
South America
Brazil, Colombia, Paraguay
  
Argentina, Chile, Ecuador, Peru
  
Deposits in Oceania Continent
  
  
Australia
Central Australia, Western Australia
  
New Zealand, Western Australia