Obsidian

Skarn

Obsidian and Skarn

Obsidian

Skarn

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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

Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin

History

Origin

Ethiopia

USA, Australia

Discoverer

Obsius

Tornebohm

Etymology

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

From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Glassy

Earthy, Mud-rich, Rough

Color

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

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Dull

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration, Paving Stone

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

As a Flux in the Production of Steel and Pig Iron, As a Sintering Agent in Steel Industry to process Iron Ore, As Dimension Stone, Gold and Silver production, Manufacture of Magnesium and Dolomite Refractories

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)

Types

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

Endoskarns

Features

Blocks negativity, Helps to protect against depression

Host Rock for Lead, Zinc and Copper Deposits

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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Skarn is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

Composition

Mineral Content

Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite

Compound Content

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

Au, CaO, Carbon Dioxide, Cu, Fe, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

5-5.56.5

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Conchoidal

Irregular

Streak

White

Light to dark brown

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Waxy and Dull

Compressive Strength

0.15 N/mm²70.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

2.4

Specific Gravity

2.6-2.72.86

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³2.8-2.9 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

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

China, India, Russia, Saudi Arabia, South Korea, Sri Lanka

Africa

Kenya

South Africa, Western Africa

Europe

Greece, Hungary, Iceland, Italy, Turkey

United Kingdom

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada

South America

Argentina, Chile, Ecuador, Peru

Brazil, Colombia, Paraguay

Deposits in Oceania Continent

Australia

New Zealand

Central Australia, Western Australia

All about Obsidian and Skarn Properties

Know all about Obsidian and Skarn properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Skarn belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Skarn is Earthy, Mud-rich, Rough. Obsidian appears Shiny and Skarn appears Dull. The luster of Obsidian is vitreous while that of Skarn is waxy and dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Skarn is available in black, brown, green, grey, white colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Skarn are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).