Definition
Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Discoverer
Georgius Agricola
Unknown
Etymology
From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Porphyritic
Color
Black, Brown, Light to Dark Grey
Black, Brown, Green, Grey, Red, Rust, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull and Soft
Dull
Interior Uses
Floor Tiles, Homes, Hotels, Kitchens
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, Paving Stone, Garden Decoration, Office Buildings
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing, Whetstones
Curbing
Construction Industry
Arrowheads, As Dimension Stone, Cobblestones, Cutting Tool, Rail Track Ballast, Roadstone
Construction Aggregate
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Commercial Uses
An Oil and Gas Reservoir, Commemorative Tablets, Creating Artwork, Used in aquariums
Creating Artwork, Gemstone, Jewelry
Types
Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite
Rhomb Porphyry
Features
Has High structural resistance against erosion and climate, Very fine grained rock
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Archaeological Significance
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean, Gateway of India in Mumbai, India, Gol Gumbaz in Karnataka, India
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Formation
Basalt forms when lava reaches the Earth's surface near an active volcano. The temperature of lava is between 1100 to 1250° C when it gets to the surface.
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.
Mineral Content
Olivine, Plagioclase, Pyroxene
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
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Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Fine Grained
Fine Grained
Fracture
Conchoidal
Irregular
Streak
White to Grey
White
Porosity
Less Porous
Less Porous
Specific Gravity
2.8-3
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
2.9-3.1 g/cm3
2.5-2.52 g/cm3
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
India, Russia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
South Africa
Egypt, Ethiopia, Ghana, South Africa
Europe
Iceland
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Deposits in Western Continents
North America
Canada, USA
Canada, Cuba, Jamaica, USA
South America
Brazil
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
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New South Wales, New Zealand, Western Australia
Basalt vs Porphyry 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. Basalt vs Porphyry characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Basalt and Properties of Porphyry. Learn more about Basalt vs Porphyry in the next section. The interior uses of Basalt include Floor tiles, Homes, Hotels and Kitchens whereas the interior uses of Porphyry include Decorative aggregates and Interior decoration. Due to some exceptional properties of Basalt and Porphyry, they have various applications in construction industry. The uses of Basalt in construction industry include Arrowheads, As dimension stone, Cobblestones, Cutting tool, Rail track ballast, Roadstone and that of Porphyry include Construction aggregate.
More about Basalt and Porphyry
Here you can know more about Basalt and Porphyry. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Basalt and Porphyry consists of mineral content and compound content. The mineral content of Basalt includes Olivine, Plagioclase, Pyroxene and mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica. You can also check out the list of all Igneous Rocks. When we have to compare Basalt vs Porphyry, the texture, color and appearance plays an important role in determining the type of rock. Basalt is available in black, brown, light to dark grey colors whereas, Porphyry is available in black, brown, green, grey, red, rust, white colors. Appearance of Basalt is Dull and Soft and that of Porphyry is Dull. Properties of rock is another aspect for Basalt vs Porphyry. The hardness of Basalt is 6 and that of Porphyry is 6-7. The types of Basalt are Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite whereas types of Porphyry are Rhomb Porphyry. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Basalt is white to grey while that of Porphyry is white. The specific heat capacity of Basalt is 0.84 kJ/Kg K and that of Porphyry is 0.71 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Basalt is heat resistant, pressure resistant, wear resistant whereas Porphyry is heat resistant, impact resistant.