Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Discoverer
Van Tooren
Unknown
Etymology
From Greek tephra, ashes from Indo-European base, to burn
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, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Porphyritic
Color
Black, Brown, Green, Grey, White
Black, Brown, Green, Grey, Red, Rust, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Vesicular
Dull
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Landscaping
Construction Aggregate
Antiquity Uses
Artifacts, Sculpture
Artifacts, Monuments, Sculpture
Commercial Uses
Production of Lime, Soil Conditioner
Creating Artwork, Gemstone, Jewelry
Types
Igneous rock
Rhomb Porphyry
Features
Host Rock for Lead
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Archaeological Significance
Formation
Tephrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive 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
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Medium to Fine Coarse Grained
Fine Grained
Fracture
Uneven
Irregular
Streak
Bluish Black
White
Porosity
Very Less Porous
Less Porous
Luster
Subvitreous to Dull
Dull
Cleavage
Crenulation and Pervasive
-
Specific Gravity
2.86
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
2.8-2.9 g/cm3
2.5-2.52 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
-
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
Namibia, Uganda
Egypt, Ethiopia, Ghana, South Africa
Europe
Germany, Hungary, Italy, Portugal, Spain
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Deposits in Western Continents
North America
USA
Canada, Cuba, Jamaica, USA
South America
-
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
New South Wales, New Zealand, Western Australia