Obsidian

Blueschist

Obsidian and Blueschist

Obsidian

Blueschist

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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

Blueschist is a metamorphic rock which is generally blue in color and is formed under conditions of high pressure and low temperature

History

Origin

Ethiopia

USA

Discoverer

Obsius

Edgar Bailey

Etymology

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

From French schiste, Greek skhistos i.e. split

Class

Igneous Rocks

Metamorphic 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

Foliated

Color

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

Blue, Bluish - Grey, Purple, Shades of Blue

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Dull and Banded

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Floor Tiles, Flooring, Homes, Hotels, Kitchens

Exterior Uses

Garden Decoration

Garden Decoration, Office Buildings

Other Architectural Uses

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

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Cemetery Markers, Commemorative Tablets, Creating Artwork, Curling, Tombstones

Types

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

Metamorphic rock

Features

Blocks negativity, Helps to protect against depression

Has High structural resistance against erosion and climate, 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.

Blueschist forms due to the metamorphism of basalt and other rocks with similar composition at high pressures and low temperatures and approximately corresponding to a depth of 15 to 30 kilometers and 200 to 500 °C.

Composition

Mineral Content

Albite, Chlorite, Epidote, Garnet, Glaucophane, Lawsonite, Muscovite or Illite, Quartz

Compound Content

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.53.5-4

1 7

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Grain Size

Fine to Medium Grained

Fracture

Conchoidal

Streak

White

White to Grey

Porosity

Very Less Porous

Highly Porous

Luster

Vitreous

Dull

Compressive Strength

0.15 N/mm²220.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.5

Specific Gravity

2.6-2.73-3.2

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 K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Impact Resistant, Pressure Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

Japan, Turkey

Africa

Kenya

Egypt, Ethiopia, South Africa

Europe

Greece, Hungary, Iceland, Italy, Turkey

France, Greece, Iceland

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

USA

South America

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

New Zealand

All about Obsidian and Blueschist Properties

Know all about Obsidian and Blueschist properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Blueschist belongs to Metamorphic Rocks.Texture of Obsidian is Glassy whereas that of Blueschist is Foliated. Obsidian appears Shiny and Blueschist appears Dull and Banded. The luster of Obsidian is vitreous while that of Blueschist is dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Blueschist is available in blue, bluish - grey, purple, shades of blue colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Blueschist are cemetery markers, commemorative tablets, creating artwork, curling, tombstones.