Mylonite

Obsidian

Mylonite and Obsidian

Mylonite

Obsidian

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Definition

Mylonite is a metamorphic rock formed by ductile deformation during intense shearing encountered during folding and faulting, a process termed cataclastic or dynamic metamorphism

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

New Zealand

Ethiopia

Discoverer

Unknown

Obsius

Etymology

From Greek mulōn mill + -ite

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

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

Texture

Foliated

Glassy

Color

Black to Grey

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull, Banded and Foilated

Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Exterior Uses

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

Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

for Road Aggregate, Landscaping, Roadstone

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Monuments

Artifacts, Jewellery

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Creating Artwork, Mirror, Used in aquariums

Types

Blastomylonites, Ultramylonites and Phyllonites

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

Features

Surfaces are often shiny

Blocks negativity, Helps to protect against depression

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Mylonites are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones.

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

Porphyroblasts

Compound Content

Aluminium Oxide, Calcium Sulfate, Chromium(III) Oxide, Iron(III) Oxide, Magnesium Carbonate, 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

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Sea Erosion, Wind Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

3-45-5.5

1 7

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Grain Size

Fine Grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Very Less Porous

Luster

Shiny

Vitreous

Compressive Strength

1.28 N/mm²0.15 N/mm²

0.15 450

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Cleavage

Conchoidal

Toughness

Specific Gravity

2.97-3.052.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.6-4.8 g/cm³2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

1.50 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India, Indonesia, Saudi Arabia, South Korea

Afghanistan, Indonesia, Japan, Russia

Africa

Eritrea, Ethiopia, Ghana, South Africa, Western Africa

Kenya

Europe

England, Finland, France, Germany, Great Britain, Greece, United Kingdom

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

Central Australia, Western Australia

New Zealand

All about Mylonite and Obsidian Properties

Know all about Mylonite and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Mylonite belongs to Metamorphic Rocks while Obsidian belongs to Igneous Rocks.Texture of Mylonite is Foliated whereas that of Obsidian is Glassy. Mylonite appears Dull, Banded and Foilated and Obsidian appears Shiny. The luster of Mylonite is shiny while that of Obsidian is vitreous. Mylonite is available in black to grey colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Mylonite are creating artwork, gemstone, jewelry and that of Obsidian are creating artwork, mirror, used in aquariums.