Obsidian

Anorthosite

Obsidian and Anorthosite

Obsidian

Anorthosite

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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

Anorthosite is a granular igneous rock composed largely of labradorite or plagioclase

History

Origin

Ethiopia

Discoverer

Obsius

Unknown

Etymology

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

From French anorthose plagioclase + -ite1

Class

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Plutonic

Other Categories

Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Glassy

Foliated, Glassy

Color

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

Black, Bluish - Grey, Brown, Green, Grey, Light Greenish Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Layered, Banded, Veined and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Floor Tiles, Homes, Interior Decoration

Exterior Uses

Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

As Dimension Stone, Cement Manufacture, for Road Aggregate

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Creating Artwork, Curling

Types

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

Proterozoic Anorthosite and Archean Anorthosite

Features

Blocks negativity, Helps to protect against depression

Generally rough to touch, Is one of the oldest 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.

Anorthosite is a phaneritic, intrusive igneous rock which is characterized by a predominance of plagioclase feldspar which is almost 90–100%, and a minimal mafic component.

Composition

Mineral Content

Amphibole, Clinopyroxene, Ilmenite, Magnetite, Olivine, Orthopyroxene

Compound Content

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

Ca, CaO, Chromium(III) Oxide, MgO, Sulfur Trioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.55-6

1 7

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Grain Size

Coarse Grained

Fracture

Conchoidal

Irregular

Streak

White

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Pearly to Subvitreous

Compressive Strength

0.15 N/mm²180.00 N/mm²

0.15 450

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Cleavage

Toughness

Specific Gravity

2.6-2.72.62-2.82

0 8.4

👆🏻

Transparency

Translucent

Density

2.6 g/cm³2.7-4 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, Impact Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

Africa

Kenya

Europe

Greece, Hungary, Iceland, Italy, Turkey

Bulgaria, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Malta, Poland, Portugal, Romania, Slovenia, Spain, Sweden, The Czech Republic

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada

South America

Argentina, Chile, Ecuador, Peru

Bolivia, Colombia

Deposits in Oceania Continent

Australia

New Zealand

Central Australia, South Australia, Western Australia

All about Obsidian and Anorthosite Properties

Know all about Obsidian and Anorthosite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Anorthosite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Anorthosite is Foliated, Glassy. Obsidian appears Shiny and Anorthosite appears Layered, Banded, Veined and Shiny. The luster of Obsidian is vitreous while that of Anorthosite is pearly to subvitreous. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Anorthosite is available in black, bluish - grey, brown, green, grey, light greenish grey, pink, white colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Anorthosite are creating artwork, curling.