Obsidian

Adakite

Obsidian and Adakite

Obsidian

Adakite

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Definition

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

Adakite is an intermediate to felsic volcanic rock that has geochemical characteristics of magma which is said to be formed by partial melting of altered basalt that is subducted below volcanic arcs

History

Origin

Ethiopia

Adak, Aleutian Islands

Discoverer

Obsius

Defant and Drummond

Etymology

From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius

From Adak, Aleutian Islands

Class

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Glassy

Porphyritic

Color

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

Black, Brown, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens

Exterior Uses

Garden Decoration

As Building Stone, As Facing Stone, Office Buildings

Other Architectural Uses

Whetstones

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Commemorative Tablets, Pottery, Used in aquariums

Types

Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian

Intermediate volcanic rock

Features

Blocks negativity, Helps to protect against depression

Has High structural resistance against erosion and climate, Host rock for Diamond, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

Adakite rocks are formed when the hydrous fluids are released from minerals that break down in metamorphosed basalt, and rise into the mantle they initiate partial melting.

Composition

Mineral Content

Olivine, Plagioclase, Pyroxene

Compound Content

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

Aluminium Oxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Coastal Erosion, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

5-5.53-4

1 7

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Grain Size

Fine to Medium Grained

Fracture

Conchoidal

Streak

White

Bluish Black

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Grainy, Pearly and Vitreous

Compressive Strength

0.15 N/mm²200.00 N/mm²

0.15 450

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Cleavage

Toughness

Specific Gravity

2.6-2.7-9999

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

India, Russia

Africa

Kenya

Ethiopia, Somalia, South Africa

Europe

Greece, Hungary, Iceland, Italy, Turkey

Iceland

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada, USA

South America

Argentina, Chile, Ecuador, Peru

Brazil

Deposits in Oceania Continent

Australia

New Zealand

All about Obsidian and Adakite Properties

Know all about Obsidian and Adakite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Adakite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Adakite is Porphyritic. Obsidian appears Shiny and Adakite appears Dull and Soft. The luster of Obsidian is vitreous while that of Adakite is grainy, pearly and vitreous. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Adakite is available in black, brown, light to dark grey colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Adakite are commemorative tablets, pottery, used in aquariums.