Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Websterite is ultramafic and ultrabasic rock that consists of roughly equal proportions of orthopyroxene and clinopyroxene. It is a special type of pyroxenite.
Origin
Egypt
Webster, North Carolina
Discoverer
Unknown
Unknown
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From the town of Webster located in North Carolina
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
Clastic, Granular, Phaneritic, Porphyritic
Color
Black, Brown, Green, Grey, Red, Rust, White
Black to Grey, Bluish - Grey, Dark Greenish - Grey, Green, Light Greenish Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull
Layered, Banded, Veined and Shiny
Interior Uses
Decorative Aggregates, Interior Decoration
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Interior Decoration
Exterior Uses
Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Construction Aggregate
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Cemetery Markers, Commemorative Tablets, Creating Artwork, Laboratory bench tops, Jewelry, Sea Defence, Tombstones
Types
Rhomb Porphyry
Ultramafic rock
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Generally rough to touch, Is one of the oldest rock
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.
Websterite can be formed as cumulates in ultramafic intrusions by accumulation of pyroxene crystals at the base of the lava chamber.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Amphibole, Augite, Bronzite, Chromite, Diopside, Enstatite, Garnet, Hornblende, Hypersthene, Magnetite, Pyroxene
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Chromium(III) Oxide, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Sulfur Trioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Impact 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, Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Coarse Grained
Fracture
Irregular
Uneven
Streak
White
White, Greenish White or Grey
Porosity
Less Porous
Less Porous
Luster
Dull
Dull to Vitreous to Submetallic
Specific Gravity
2.5-4
3.2-3.5
Transparency
Translucent to Opaque
Opaque
Density
2.5-2.52 g/cm3
3.1-3.6 g/cm3
Resistance
Heat Resistant, Impact Resistant
Impact 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
Germany, Greece, Italy, Scotland, Turkey
Others
Greenland
Greenland
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Brazil, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
New Zealand, Queensland
All about Porphyry and Websterite Properties
Know all about Porphyry and Websterite properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry and Websterite belong to Igneous Rocks.Texture of Porphyry is Porphyritic whereas that of Websterite is Clastic, Granular, Phaneritic, Porphyritic. Porphyry appears Dull and Websterite appears Layered, Banded, Veined and Shiny. The luster of Porphyry is dull while that of Websterite is dull to vitreous to submetallic. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Websterite is available in black to grey, bluish - grey, dark greenish - grey, green, light greenish grey colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Websterite are cemetery markers, commemorative tablets, creating artwork, laboratory bench tops, jewelry, sea defence, tombstones.