Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
  
Dunite is a green to brownish coarse-grained igneous rock mainly consisting of olivine
  
History
  
  
Origin
Egypt
  
New Zealand
  
Discoverer
Unknown
  
Ferdinand von Hochstetter
  
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
  
From the name of Dun Mountain, New Zealand, + -ite1
  
Class
Igneous Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Hard Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Plutonic
  
Plutonic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Coarse Grained Rock, Opaque Rock
  
Texture
Porphyritic
  
Phaneritic
  
Color
Black, Brown, Colourless, Green, Grey, Red, Rust, White
  
Dark Greenish - Grey
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
Yes
  
Yes
  
Wind Resistant
No
  
No
  
Acid Resistant
Yes
  
No
  
Appearance
Dull
  
Rough and Shiny
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Interior Decoration
  
Decorative Aggregates, Interior Decoration
  
Exterior Uses
Garden Decoration, Paving Stone
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
Construction Aggregate
  
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture
  
Artifacts, Monuments, Sculpture, Small Figurines
  
Other Uses
  
  
Commercial Uses
Creating Artwork, Gemstone, Jewelry
  
Creating Artwork, Gemstone, Jewelry, Source of Chromite, Platinum, Nickel and Garnet, Source of Diamonds
  
Types
Rhomb Porphyry
  
Not Available
  
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
  
Constitutes upper part of the Earth's mantle, Generally rough to touch, Host rock for Diamond, Is one of the oldest rock
  
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
  
Used
  
Petroglyphs
Not Used
  
Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Absent
  
Formation
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.
  
Dunite is a plutonic ultramafic igneous rock consisting almost m olivine. It can be formed in two ways.
  
Composition
  
  
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
  
Amphibole, Chromite, Garnet, Magnesium, Olivine, Phlogopite, Plagioclase, Pyroxene
  
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Ca, CaO, Fe, Potassium, Silicon Dioxide, Sodium, Titanium Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Not Registered
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
  
Coastal Erosion, Glacier Erosion, Water Erosion
  
Physical Properties
  
  
Hardness
6-7
  
3.5-4
  
Grain Size
Fine Grained
  
Coarse Grained
  
Fracture
Irregular
  
Irregular
  
Streak
White
  
White
  
Porosity
Less Porous
  
Less Porous
  
Luster
Dull
  
Shiny
  
Compressive Strength
Not Available
  
107.55 N/mm
2
  
19
Cleavage
Imperfect
  
Imperfect
  
Toughness
1.7
  
2.1
  
Specific Gravity
2.5-4
  
3-3.01
  
Transparency
Translucent to Opaque
  
Translucent to Opaque
  
Density
2.5-2.52 g/cm3
  
2.84-2.85 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
1.25 kJ/Kg K
  
6
Resistance
Heat Resistant, Impact Resistant
  
Heat Resistant, Pressure Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
  
China, India, Indonesia, Kazakhstan, Russia, South Korea, Thailand, Turkey
  
Africa
Egypt, Ethiopia, Ghana, South Africa
  
Morocco, South Africa
  
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
  
Finland, France, Georgia, Germany, Great Britain, Italy, Kazakhstan, Netherlands, Norway, Spain, Switzerland, Venezuela
  
Others
Greenland
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, Cuba, Jamaica, USA
  
Canada, USA
  
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
  
Argentina, Brazil, Colombia, Ecuador, Venezuela
  
Deposits in Oceania Continent
  
  
Australia
New South Wales, New Zealand, Western Australia
  
New Zealand, Western Australia