Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth
Discoverer
Van Tooren
Obsius
Etymology
From Greek tephra, ashes from Indo-European base, to burn
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Opaque Rock
Texture
Aphanitic to Porphyritic
Glassy
Color
Black, Brown, Colourless, Green, Grey, White
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Vesicular
Shiny
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
Other Architectural Uses
Curbing
Not Yet Used
Construction Industry
Landscaping
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Medical Industry
Not Yet Used
Surgery
Antiquity Uses
Artifacts, Sculpture
Artifacts, Jewellery
Commercial Uses
Production of Lime, Soil Conditioner
Creating Artwork, Mirror, Used in aquariums
Types
Not Available
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Features
Host Rock for Lead
Blocks negativity, Helps to protect against depression
Archaeological Significance
Monuments
Not Yet Used
Not Yet Used
Famous Monuments
Not Applicable
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Used
Not Yet Used
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.
When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.
Mineral Content
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Not Available
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical 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
Not Applicable
Fracture
Uneven
Conchoidal
Streak
Bluish Black
White
Porosity
Very Less Porous
Very Less Porous
Luster
Subvitreous to Dull
Vitreous
Cleavage
Crenulation and Pervasive
Non-Existent
Toughness
2.4
Not Available
Specific Gravity
2.86
2.6-2.7
Transparency
Opaque
Translucent
Density
2.8-2.9 g/cm3
2.6 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
Not Yet Found
Afghanistan, Indonesia, Japan, Russia
Africa
Namibia, Uganda
Kenya
Europe
Germany, Hungary, Italy, Portugal, Spain
Greece, Hungary, Iceland, Italy, Turkey
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
Not Yet Found
Argentina, Chile, Ecuador, Peru
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
New Zealand
All about Tephrite and Obsidian Properties
Know all about Tephrite and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Tephrite and Obsidian belong to Igneous Rocks.Texture of Tephrite is Aphanitic to Porphyritic whereas that of Obsidian is Glassy. Tephrite appears Vesicular and Obsidian appears Shiny. The luster of Tephrite is subvitreous to dull while that of Obsidian is vitreous. Tephrite is available in black, brown, colourless, green, grey, white colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Tephrite are production of lime, soil conditioner and that of Obsidian are creating artwork, mirror, used in aquariums.