Definition
Granite is a very hard, granular, crystalline igneous rock which consists mainly of quartz, mica, and feldspar and is often used as building stone
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Discoverer
Alexander von Humboldt
Unknown
Etymology
From Italian granito, which means grained rock, from grano grain, and from Latin granum
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Granular, Phaneritic
Porphyritic
Color
Black, Grey, Orange, Pink, White
Black, Brown, Green, Grey, Red, Rust, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Veined or Pebbled
Dull
Interior Uses
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Bridges, Paving Stone, Garden Decoration, Near Swimming Pools, Office Buildings, Resorts
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone
Construction Aggregate
Antiquity Uses
Monuments, Sculpture, Small Figurines
Artifacts, Monuments, Sculpture
Commercial Uses
Curling, Gemstone, Laboratory bench tops, Tombstones, Used in aquariums
Creating Artwork, Gemstone, Jewelry
Types
Igneous Protolith Granite, Sedimentary Protolith Granite, Mantle Granite, Anorogenic Granite, Hybrid Granite, Granodiorite and Alkali Feldspar Granite
Rhomb Porphyry
Features
Available in Lots of Colors and Patterns, It is One of the Oldest, Strongest and Hardest Rock
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Archaeological Significance
Famous Monuments
Agia Sophia in Istanbul, Turkey, Blue Domed Church in Santorini, Greece, Blue Mosque in Istanbul, Charminar in Hyderabad, India, Diana, Princess of Wales Memorial Fountain in London, UK, Ephesus in Turkey, Georgia Guidestones in Georgia, US, Hermitage in Saint Petersburg, Khajuraho Temples, India, Mahabalipuram in Tamil Nadu, India, Mysore Palace in Karnataka, India, Signers Monument in Augusta, Georgia, Statue of Liberty in New York, USA, Taj Mahal in Agra, India, Tower Bridge in London, Vietnam Veterans Memorial in Washington, US, Washington Monument, US
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Famous Sculptures
Avukana Buddha Statue in Sri Lanka, Lincoln Memorial in America, Mount Rushmore National Memorial in South Dakota, US, The Colossal Red Granite Statue of Amenhotep III in Karnak, Egypt
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Formation
Granite is an intrusive igneous rock which is very hard, crystalline and is visibly homogeneous in texture and forms by melting of continental rocks
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
Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz
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
Burial Metamorphism, Cataclastic 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
Chemical Erosion, Sea Erosion, Water Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Large and Coarse Grained
Fine Grained
Porosity
Less Porous
Less Porous
Luster
Dull to Grainy with Sporadic parts Pearly and Vitreous
Dull
Specific Gravity
2.6-2.7
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
2.65-2.75 g/cm3
2.5-2.52 g/cm3
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Egypt, Ethiopia, Ghana, South Africa
Europe
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland, The Czech Republic
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
-
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
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New South Wales, New Zealand, Western Australia