Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
History
Origin
Brazil
Western Australia, Minnesota
Discoverer
Unknown
Johann Gottlob Lehmann
Etymology
from French néphéline, from Greek nephelē
From its formation process
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
-
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Aphanitic
Banded, Trellis
Color
Black, Brown, Green, Grey, White
Red, Reddish Brown
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Skeletal
Layered, Banded, Veined and Shiny
Architecture
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Paving Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Industry
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts
Other Uses
Commercial Uses
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
As a touchstone, Cemetery Markers, Creating Artwork
Types
Peralkaline Nephelinite
Algoma-type , Lake Superior-type, Superior-type and Taconite
Features
Host Rock for Lead
Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Present
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.
The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
Composition
Mineral Content
Clinopyroxene, Nepheline, Plagioclase
Hematite, Magnetite, Quartz
Compound Content
Ca, CaO, Carbon, Cl, MgO
Fe, Iron(III) Oxide, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Contact Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Coastal Erosion, Wind Erosion
Physical Properties
Hardness
6.55.5-6
1
7
👆🏻
Grain Size
Fine Grained
Large and Coarse Grained
Fracture
Flat
Uneven, Splintery or Conchoidal
Streak
White
White
Porosity
Less Porous
Highly Porous
Luster
Vitreous to Metallic
Earthy
Compressive Strength
35.00 N/mm2220.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
2.7
1.5
Specific Gravity
2.4-2.95.0-5.3
0
8.4
👆🏻
Transparency
Opaque
Translucent to Opaque
Density
2.5-3 g/cm3-9999 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.88 kJ/Kg K3.20 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Japan
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Rwanda, Tanzania
Kenya, Morocco, South Africa, Tanzania
Europe
-
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Hawaii Islands
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Colombia
Bolivia, Brazil
Deposits in Oceania Continent
Australia
-
New South Wales, Queensland, South Australia, Western Australia