Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth
Discoverer
Unknown
Georgius Agricola
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Porphyritic
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Color
Black, Brown, Green, Grey, Red, Rust, White
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull
Dull and Soft
Interior Uses
Decorative Aggregates, Interior Decoration
Floor Tiles, Homes, Hotels, Kitchens
Exterior Uses
Garden Decoration, Paving Stone
As Building Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Construction Industry
Construction Aggregate
Arrowheads, As Dimension Stone, Cobblestones, Cutting Tool, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments
Commercial Uses
Creating Artwork, Gemstone, Jewelry
An Oil and Gas Reservoir, Commemorative Tablets, Creating Artwork, Used in aquariums
Types
Rhomb Porphyry
Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Has High structural resistance against erosion and climate, Very fine grained rock
Archaeological Significance
Famous Monuments
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Easter Island in the Polynesian Triangle, Pacific Ocean, Gateway of India in Mumbai, India, Gol Gumbaz in Karnataka, India
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.
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.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Olivine, Plagioclase, Pyroxene
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
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Grain Size
Fine Grained
Fine Grained
Fracture
Irregular
Conchoidal
Streak
White
White to Grey
Porosity
Less Porous
Less Porous
Specific Gravity
2.5-4
2.8-3
Transparency
Translucent to Opaque
Opaque
Density
2.5-2.52 g/cm3
2.9-3.1 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
India, Russia
Africa
Egypt, Ethiopia, Ghana, South Africa
South Africa
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Iceland
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
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All about Porphyry and Basalt Properties
Know all about Porphyry and Basalt properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry and Basalt belong to Igneous Rocks.Texture of Porphyry is Porphyritic whereas that of Basalt is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Porphyry appears Dull and Basalt appears Dull and Soft. The luster of Porphyry is dull while that of Basalt is . Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Basalt is available in black, brown, light to dark grey colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Basalt are an oil and gas reservoir, commemorative tablets, creating artwork, used in aquariums.