Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
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
Origin
Brazil
Adak, Aleutian Islands
Discoverer
Unknown
Defant and Drummond
Etymology
from French néphéline, from Greek nephelē
From Adak, Aleutian Islands
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Aphanitic
Porphyritic
Color
Black, Brown, Green, Grey, White
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Appearance
Skeletal
Dull and Soft
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Office Buildings
Other Architectural Uses
Curbing
Whetstones
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Monuments, Sculpture, Small Figurines
Commercial Uses
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
Commemorative Tablets, Pottery, Used in aquariums
Types
Peralkaline Nephelinite
Intermediate volcanic rock
Features
Host Rock for Lead
Has High structural resistance against erosion and climate, Host rock for Diamond, Very fine grained rock
Archaeological Significance
Formation
Nephelinite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
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.
Mineral Content
Clinopyroxene, Nepheline, Plagioclase
Olivine, Plagioclase, Pyroxene
Compound Content
Ca, CaO, Carbon, Cl, MgO
Aluminium Oxide, MgO, Silicon Dioxide
Types of Metamorphism
Contact Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Coastal Erosion, Sea Erosion, Water Erosion
Grain Size
Fine Grained
Fine to Medium Grained
Streak
White
Bluish Black
Porosity
Less Porous
Less Porous
Luster
Vitreous to Metallic
Grainy, Pearly and Vitreous
Specific Gravity
2.4-2.9
-9999
Transparency
Opaque
Opaque
Density
2.5-3 g/cm3
-9999 g/cm3
Resistance
Heat Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Africa
Rwanda, Tanzania
Ethiopia, Somalia, South Africa
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Colombia
Brazil
Deposits in Oceania Continent
All about Nephelinite and Adakite Properties
Know all about Nephelinite and Adakite properties here. All properties of rocks are important as they define the type of rock and its application. Nephelinite and Adakite belong to Igneous Rocks.Texture of Nephelinite is Aphanitic whereas that of Adakite is Porphyritic. Nephelinite appears Skeletal and Adakite appears Dull and Soft. The luster of Nephelinite is vitreous to metallic while that of Adakite is grainy, pearly and vitreous. Nephelinite is available in black, brown, green, grey, white colors whereas Adakite is available in black, brown, light to dark grey colors. The commercial uses of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo) and that of Adakite are commemorative tablets, pottery, used in aquariums.