Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine
Origin
Brazil
Hawaii Islands
Discoverer
Unknown
Unknown
Etymology
from French néphéline, from Greek nephelē
From Greek pikros bitter + -ite, 19th century
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic
Earthy, Rough
Color
Black, Brown, Colourless, Green, Grey, White
Black, Brown, Colourless, Green, Grey, Pink, White, Yellow
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Skeletal
Rough and Shiny
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Countertops, Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments, Sculpture
Commercial Uses
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)
Types
Peralkaline Nephelinite
Oceanite
Features
Host Rock for Lead
Host Rock for Lead
Archaeological Significance
Famous Monuments
Data Not Available
Data Not Available
Famous Sculptures
Data Not Available
Data Not Available
Pictographs
Not Used
Not Used
Petroglyphs
Not Used
Not Used
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.
Picrite 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.
Mineral Content
Clinopyroxene, Nepheline, Plagioclase
Biotite, Olivine, Plagioclase, Pyrrhotite
Compound Content
Ca, CaO, Carbon, Cl, MgO
Al, CaO, Carbon Dioxide, Mg, MgO
Types of Metamorphism
Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Fine Grained
Streak
White
White, Greenish White or Grey
Porosity
Less Porous
Less Porous
Luster
Vitreous to Metallic
Subvitreous to Dull
Cleavage
Imperfect
Imperfect
Specific Gravity
2.4-2.9
2.75-2.92
Transparency
Opaque
Opaque
Density
2.5-3 g/cm3
1.5-2.5 g/cm3
Resistance
Heat Resistant
Heat Resistant
Deposits in Eastern Continents
Africa
Rwanda, Tanzania
South Africa
Europe
Not Yet Found
Iceland
Others
Hawaii Islands
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Colombia
Brazil
Deposits in Oceania Continent
Australia
Not Yet Found
Not Yet Found
All about Nephelinite and Picrite Properties
Know all about Nephelinite and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Nephelinite and Picrite belong to Igneous Rocks.Texture of Nephelinite is Aphanitic whereas that of Picrite is Earthy, Rough. Nephelinite appears Skeletal and Picrite appears Rough and Shiny. The luster of Nephelinite is vitreous to metallic while that of Picrite is subvitreous to dull. Nephelinite is available in black, brown, colourless, green, grey, white colors whereas Picrite is available in black, brown, colourless, green, grey, pink, white, yellow colors. The commercial uses of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo) and that of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).