Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Rhyolite is a fine-grained igneous rock which is rich in silica
Origin
Egypt
North America
Discoverer
Unknown
Ferdinand von Richthofen
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From German Rhyolit, from Greek rhuax lava stream + lithos stone
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Porphyritic
Aphanitic, Glassy, Porphyritic
Color
Black, Brown, Green, Grey, Red, Rust, White
Grey, White, Light Black
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Exterior Uses
Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
Other Architectural Uses
Curbing
-
Construction Industry
Construction Aggregate
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Gemstone, Laboratory bench tops, Jewelry
Types
Rhomb Porphyry
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Acidic in nature, Available in lots of colors
Archaeological Significance
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.
Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
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
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Large and Coarse Grained
Fracture
Irregular
Sub-conchoidal
Porosity
Less Porous
Highly Porous
Specific Gravity
2.5-4
2.65-2.67
Transparency
Translucent to Opaque
Opaque
Density
2.5-2.52 g/cm3
2.4-2.6 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
China, India
Africa
Egypt, Ethiopia, Ghana, South Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Germany, Iceland, Ireland, Italy, Spain
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
New Zealand, Queensland, Western Australia
Porphyry vs Rhyolite 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 Rhyolite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Porphyry and Properties of Rhyolite. Learn more about Porphyry vs Rhyolite in the next section. The interior uses of Porphyry include Decorative aggregates and Interior decoration whereas the interior uses of Rhyolite include Decorative aggregates, Homes, Hotels, Interior decoration and Kitchens. Due to some exceptional properties of Porphyry and Rhyolite, they have various applications in construction industry. The uses of Porphyry in construction industry include Construction aggregate and that of Rhyolite include Arrowheads, As dimension stone, Building houses or walls, Construction aggregate, Cutting tool, For road aggregate, Knives.
More about Porphyry and Rhyolite
Here you can know more about Porphyry and Rhyolite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Porphyry and Rhyolite consists of mineral content and compound content. The mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica and mineral content of Rhyolite includes Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz. You can also check out the list of all Igneous Rocks. When we have to compare Porphyry vs Rhyolite, the texture, color and appearance plays an important role in determining the type of rock. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas, Rhyolite is available in grey, white, light black colors. Appearance of Porphyry is Dull and that of Rhyolite is Banded. Properties of rock is another aspect for Porphyry vs Rhyolite. Hardness of Porphyry and Rhyolite is 6-7. The types of Porphyry are Rhomb Porphyry whereas types of Rhyolite are Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.. 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 Rhyolite is . The specific heat capacity of Porphyry is 0.71 kJ/Kg K and that of Rhyolite 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.Porphyry is heat resistant, impact resistant whereas Rhyolite is heat resistant, wear resistant.