Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Banded iron formation are distinctive units of sedimentary rock that are almost always of Precambrian age
Origin
Egypt
Western Australia, Minnesota
Discoverer
Unknown
Unknown
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From its formation process
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Group
Plutonic
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Porphyritic
Banded, Trellis
Color
Black, Brown, Colourless, Green, Grey, Red, Rust, White
Red, Reddish Brown
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull
Layered, Banded, Veined and Shiny
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
Garden Decoration, Paving Stone
Paving Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Construction Industry
Construction Aggregate
As Dimension Stone, Used for flooring, stair treads, borders and window sills.
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts
Commercial Uses
Creating Artwork, Gemstone, Jewelry
As a touchstone, Cemetery Markers, Creating Artwork
Types
Rhomb Porphyry
Algoma-type , Lake Superior-type, Superior-type and Taconite
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Is one of the oldest rock
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Data Not Available
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Not Used
Not Used
Petroglyphs
Not Used
Not Used
Figurines
Used
Not Yet Used
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.
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.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Hematite, Magnetite, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Not Registered
Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Coastal Erosion, Wind Erosion
Grain Size
Fine Grained
Large and Coarse Grained
Fracture
Irregular
Uneven, Splintery or Conchoidal
Porosity
Less Porous
Highly Porous
Cleavage
Imperfect
Imperfect
Specific Gravity
2.5-4
5.0-5.3
Transparency
Translucent to Opaque
Translucent to Opaque
Density
2.5-2.52 g/cm3
Not Available
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
China, India, Iran, Iraq, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Egypt, Ethiopia, Ghana, South Africa
Kenya, Morocco, South Africa, Tanzania
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Greenland
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, Mexico, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
New South Wales, Queensland, South Australia, Western Australia
Porphyry vs Banded iron formation Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Porphyry vs Banded iron formation characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Porphyry and Properties of Banded iron formation. Learn more about Porphyry vs Banded iron formation in the next section. The interior uses of Porphyry include Decorative aggregates and Interior decoration whereas the interior uses of Banded iron formation include Decorative aggregates and Homes. Due to some exceptional properties of Porphyry and Banded iron formation, they have various applications in construction industry. The uses of Porphyry in construction industry include Construction aggregate and that of Banded iron formation include As dimension stone, Used for flooring, stair treads, borders and window sills..
More about Porphyry and Banded iron formation
Here you can know more about Porphyry and Banded iron formation. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Porphyry and Banded iron formation consists of mineral content and compound content. The mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica and mineral content of Banded iron formation includes Hematite, Magnetite, Quartz. You can also check out the list of all Igneous Rocks. When we have to compare Porphyry vs Banded iron formation, the texture, color and appearance plays an important role in determining the type of rock. Porphyry is available in black, brown, colourless, green, grey, red, rust, white colors whereas, Banded iron formation is available in red, reddish brown colors. Appearance of Porphyry is Dull and that of Banded iron formation is Layered, Banded, Veined and Shiny. Properties of rock is another aspect for Porphyry vs Banded iron formation. The hardness of Porphyry is 6-7 and that of Banded iron formation is 5.5-6. The types of Porphyry are Rhomb Porphyry whereas types of Banded iron formation are Algoma-type , Lake Superior-type, Superior-type and Taconite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Porphyry and Banded iron formation is white. The specific heat capacity of Porphyry is Not Available and that of Banded iron formation is 3.20 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Porphyry is heat resistant, impact resistant whereas Banded iron formation is heat resistant, impact resistant, pressure resistant, wear resistant.