Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds
Discoverer
Unknown
John Peter Salley
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From the Old English term col, which has meant mineral of fossilized carbon since the 13th century
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Group
Plutonic
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Porphyritic
Amorphous, Glassy
Color
Black, Brown, Colourless, Green, Grey, Red, Rust, White
Black, Brown, Dark Brown, Grey, Light to Dark Grey
Durability
Durable
Durable
Appearance
Dull
Veined or Pebbled
Interior Uses
Decorative Aggregates, Interior Decoration
Not Yet Used
Exterior Uses
Garden Decoration, Paving Stone
Not Yet Used
Other Architectural Uses
Curbing
Not Yet Used
Construction Industry
Construction Aggregate
Cement Manufacture, for Road Aggregate, Making natural cement, Steel Production
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Alumina Refineries, Electricity Generation, Liquid Fuel, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Paper Industry
Types
Rhomb Porphyry
Peat, Lignite, Sub-Bituminous Coal, Bituminous Coal, Anthracite, Graphite
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Helps in production of Heat and Electricity, Used as fossil fuel
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.
Coal forms from the accumulation of plant debris in a swamp environment which is buried by sediments such as mud or sand and then compacted to form coal.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Analcime, Apatite, Barite, Calcite, Chalcopyrite, Chlorite, Chromite, Clausthalite, Clay Minerals, Crandallite Group, Dolomite, Feldspar, Galena, Gypsum, Marcasite, Muscovite or Illite, Pyrite, Quartz, Siderite, Sphalerite, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Not Registered
Not Applicable
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Not Applicable
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Fracture
Irregular
Conchoidal
Porosity
Less Porous
Less Porous
Luster
Dull
Dull to Vitreous to Submetallic
Cleavage
Imperfect
Non-Existent
Toughness
1.7
Not Available
Specific Gravity
2.5-4
1.1-1.4
Transparency
Translucent to Opaque
Opaque
Density
2.5-2.52 g/cm3
1100-1400 g/cm3
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Bangladesh, Burma, Cambodia, China, India, Indonesia, Kazakhstan, Malaysia, Mongolia, Pakistan, Turkey, Vietnam
Africa
Egypt, Ethiopia, Ghana, South Africa
Botswana, Kenya, Morocco, Mozambique, South Africa, Tanzania
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Belgium, Bulgaria, England, France, Germany, Greece, Hungary, Kosovo, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, The Czech Republic, Ukraine, United Kingdom
Others
Greenland
Not Yet Found
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, Mexico, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Brazil, Chile, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
New South Wales, Queensland, Victoria
Porphyry vs Coal 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 Coal characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Porphyry and Properties of Coal. Learn more about Porphyry vs Coal in the next section. The interior uses of Porphyry include Decorative aggregates and Interior decoration whereas the interior uses of Coal include Not yet used. Due to some exceptional properties of Porphyry and Coal, they have various applications in construction industry. The uses of Porphyry in construction industry include Construction aggregate and that of Coal include Cement manufacture, For road aggregate, Making natural cement, Steel production.
More about Porphyry and Coal
Here you can know more about Porphyry and Coal. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Porphyry and Coal consists of mineral content and compound content. The mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica and mineral content of Coal includes Analcime, Apatite, Barite, Calcite, Chalcopyrite, Chlorite, Chromite, Clausthalite, Clay Minerals, Crandallite Group, Dolomite, Feldspar, Galena, Gypsum, Marcasite, Muscovite or Illite, Pyrite, Quartz, Siderite, Sphalerite, Zircon. You can also check out the list of all Igneous Rocks. When we have to compare Porphyry vs Coal, 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, Coal is available in black, brown, dark brown, grey, light to dark grey colors. Appearance of Porphyry is Dull and that of Coal is Veined or Pebbled. Properties of rock is another aspect for Porphyry vs Coal. The hardness of Porphyry is 6-7 and that of Coal is 1-1.5. The types of Porphyry are Rhomb Porphyry whereas types of Coal are Peat, Lignite, Sub-Bituminous Coal, Bituminous Coal, Anthracite, Graphite. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Porphyry is white while that of Coal is black. The specific heat capacity of Porphyry is Not Available and that of Coal is 1.32 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 Coal is heat resistant.