Definition
Adakite is an intermediate to felsic volcanic rock that has geochemical characteristics of magma which is said to be formed by partial melting of altered basalt that is subducted below volcanic arcs
  
Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin
  
History
  
  
Origin
Adak, Aleutian Islands
  
USA, Australia
  
Discoverer
Defant and Drummond
  
Tornebohm
  
Etymology
From Adak, Aleutian Islands
  
From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.
  
Class
Igneous Rocks
  
Metamorphic Rocks
  
Sub-Class
Durable Rock, Medium Hardness Rock
  
Durable Rock, Hard Rock
  
Family
  
  
Group
Volcanic
  
Not Applicable
  
Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Porphyritic
  
Earthy, Mud-rich, Rough
  
Color
Black, Brown, Light to Dark Grey
  
Black, Brown, Colourless, Green, Grey, White
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
No
  
Yes
  
Stain Resistant
No
  
No
  
Wind Resistant
Yes
  
Yes
  
Acid Resistant
Yes
  
Yes
  
Appearance
Dull and Soft
  
Dull
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens
  
Decorative Aggregates, Entryways, Interior Decoration
  
Exterior Uses
As Building Stone, As Facing Stone, Office Buildings
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Whetstones
  
Curbing
  
Industry
  
  
Construction Industry
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
  
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
  
Medical Industry
Not Yet Used
  
Not Applicable
  
Antiquity Uses
Monuments, Sculpture, Small Figurines
  
Artifacts, Monuments, Sculpture
  
Other Uses
  
  
Commercial Uses
Commemorative Tablets, Pottery, Used in aquariums
  
Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)
  
Types
Not Available
  
Endoskarns
  
Features
Has High structural resistance against erosion and climate, Host rock for Diamond, Very fine grained rock
  
Host Rock for Lead, Zinc and Copper Deposits
  
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
  
Not Used
  
Petroglyphs
Used
  
Not Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Absent
  
Formation
Adakite rocks are formed when the hydrous fluids are released from minerals that break down in metamorphosed basalt, and rise into the mantle they initiate partial melting.
  
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.
  
Composition
  
  
Mineral Content
Olivine, Plagioclase, Pyroxene
  
Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite
  
Compound Content
Aluminium Oxide, MgO, Silicon Dioxide
  
Au, CaO, Carbon Dioxide, Cu, Fe, MgO
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
No
  
Types of Weathering
Chemical Weathering, Mechanical Weathering
  
Not Applicable
  
Erosion
Yes
  
No
  
Types of Erosion
Coastal Erosion, Sea Erosion, Water Erosion
  
Not Applicable
  
Physical Properties
  
  
Hardness
3-4
  
6.5
  
Grain Size
Fine to Medium Grained
  
Fine Grained
  
Fracture
Conchoidal
  
Irregular
  
Streak
Bluish Black
  
Light to dark brown
  
Porosity
Less Porous
  
Less Porous
  
Luster
Grainy, Pearly and Vitreous
  
Waxy and Dull
  
Cleavage
Not Available
  
Slaty
  
Toughness
Not Available
  
2.4
  
Specific Gravity
Not Available
  
2.86
  
Transparency
Opaque
  
Opaque
  
Density
Not Available
  
2.8-2.9 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
0.92 kJ/Kg K
  
10
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant
  
Deposits in Eastern Continents
  
  
Asia
India, Russia
  
China, India, Russia, Saudi Arabia, South Korea, Sri Lanka
  
Africa
Ethiopia, Somalia, South Africa
  
South Africa, Western Africa
  
Europe
Iceland
  
United Kingdom
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
Canada
  
South America
Brazil
  
Brazil, Colombia, Paraguay
  
Deposits in Oceania Continent
  
  
Australia
Not Yet Found
  
Central Australia, Western Australia