Definition
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
  
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
  
History
  
  
Origin
Brazil
  
Egypt
  
Discoverer
Unknown
  
Unknown
  
Etymology
from French néphéline, from Greek nephelē
  
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
  
Class
Igneous Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Hard Rock
  
Durable Rock, Hard Rock
  
Family
  
  
Group
Plutonic
  
Plutonic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Aphanitic
  
Porphyritic
  
Color
Black, Brown, Colourless, Green, Grey, White
  
Black, Brown, Colourless, Green, Grey, Red, Rust, White
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
No
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
Yes
  
Yes
  
Wind Resistant
Yes
  
No
  
Acid Resistant
Yes
  
Yes
  
Appearance
Skeletal
  
Dull
  
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
  
Garden Decoration, Paving Stone
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
  
Construction Aggregate
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Monuments, Sculpture
  
Other Uses
  
  
Commercial Uses
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
  
Creating Artwork, Gemstone, Jewelry
  
Types
Peralkaline Nephelinite
  
Rhomb Porphyry
  
Features
Host Rock for Lead
  
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
  
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
Not Used
  
Not Used
  
Petroglyphs
Not Used
  
Not Used
  
Figurines
Used
  
Used
  
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.
  
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
  
Composition
  
  
Mineral Content
Clinopyroxene, Nepheline, Plagioclase
  
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
  
Compound Content
Ca, CaO, Carbon, Cl, MgO
  
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Contact Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Not Registered
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Coastal Erosion, Glacier Erosion
  
Physical Properties
  
  
Hardness
6.5
  
6-7
  
Grain Size
Fine Grained
  
Fine Grained
  
Fracture
Flat
  
Irregular
  
Streak
White
  
White
  
Porosity
Less Porous
  
Less Porous
  
Luster
Vitreous to Metallic
  
Dull
  
Compressive Strength
35.00 N/mm
2
  
29
Not Available
  
Cleavage
Imperfect
  
Imperfect
  
Toughness
2.7
  
1.7
  
Specific Gravity
2.4-2.9
  
2.5-4
  
Transparency
Opaque
  
Translucent to Opaque
  
Density
2.5-3 g/cm3
  
2.5-2.52 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.88 kJ/Kg K
  
13
Not Available
  
Resistance
Heat Resistant
  
Heat Resistant, Impact Resistant
  
Deposits in Eastern Continents
  
  
Asia
Japan
  
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
  
Africa
Rwanda, Tanzania
  
Egypt, Ethiopia, Ghana, South Africa
  
Europe
Not Yet Found
  
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
  
Others
Hawaii Islands
  
Greenland
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
Canada, Cuba, Jamaica, USA
  
South America
Colombia
  
Bolivia, Brazil, Colombia, Ecuador, Paraguay
  
Deposits in Oceania Continent
  
  
Australia
Not Yet Found
  
New South Wales, New Zealand, Western Australia