Tephrite

Obsidian

Tephrite and Obsidian

Tephrite

Obsidian

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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

History

Origin

Germany

Ethiopia

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

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Opaque Rock

Texture

Aphanitic to Porphyritic

Glassy

Color

Black, Brown, Green, Grey, White

Black, Blue, Brown, Green, Orange, Red, Tan, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Shiny

Uses

Architecture

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

Industry

Construction Industry

Landscaping

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Sculpture

Artifacts, Jewellery

Other Uses

Commercial Uses

Production of Lime, Soil Conditioner

Creating Artwork, Mirror, Used in aquariums

Types

Igneous rock

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

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Composition

Mineral Content

Alkali feldspar, Nepheline, Plagioclase, Pyroxene

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6.55-5.5

1 7

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Grain Size

Medium to Fine Coarse Grained

Fracture

Uneven

Conchoidal

Streak

Bluish Black

White

Porosity

Very Less Porous

Luster

Subvitreous to Dull

Vitreous

Compressive Strength

90.00 N/mm²0.15 N/mm²

0.15 450

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Cleavage

Crenulation and Pervasive

Toughness

2.4

Specific Gravity

2.862.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.8-2.9 g/cm³2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

Africa

Namibia, Uganda

Kenya

Europe

Germany, Hungary, Italy, Portugal, Spain

Greece, Hungary, Iceland, Italy, Turkey

Others

Deposits in Western Continents

North America

USA

Canada, Mexico, USA

South America

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, 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.