Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism
History
Origin
Brazil
New Zealand
Discoverer
Unknown
Unknown
Etymology
from French néphéline, from Greek nephelē
From Greek mulōn mill + -ite
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
-
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic
Foliated
Color
Black, Brown, Green, Grey, White
Black to Grey
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Skeletal
Dull, Banded and Foilated
Architecture
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
for Road Aggregate, Landscaping, Roadstone
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
Other Uses
Commercial Uses
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
Creating Artwork, Gemstone, Jewelry
Types
Peralkaline Nephelinite
Blastomylonites, Ultramylonites and Phyllonites
Features
Host Rock for Lead
Surfaces are often shiny
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
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.
Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.
Composition
Mineral Content
Clinopyroxene, Nepheline, Plagioclase
Porphyroblasts
Compound Content
Ca, CaO, Carbon, Cl, MgO
Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, Silicon Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Contact Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Physical Properties
Hardness
6.53-4
1
7
👆🏻
Grain Size
Fine Grained
Fine Grained
Fracture
Flat
Conchoidal
Streak
White
White
Porosity
Less Porous
Highly Porous
Luster
Vitreous to Metallic
Shiny
Compressive Strength
35.00 N/mm21.28 N/mm2
0.15
450
👆🏻
Cleavage
-
Conchoidal
Toughness
2.7
-
Specific Gravity
2.4-2.92.97-3.05
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
2.5-3 g/cm32.6-4.8 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.88 kJ/Kg K1.50 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
Japan
China, India, Indonesia, Saudi Arabia, South Korea
Africa
Rwanda, Tanzania
Eritrea, Ethiopia, Ghana, South Africa, Western Africa
Europe
-
England, Finland, France, Germany, Great Britain, Greece, United Kingdom
Others
Hawaii Islands
-
Deposits in Western Continents
North America
Canada, USA
USA
South America
Colombia
-
Deposits in Oceania Continent
Australia
-
Central Australia, Western Australia