Obsidian

Basalt

Obsidian and Basalt

Obsidian

Basalt

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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

Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth

History

Origin

Ethiopia

Egypt

Discoverer

Obsius

Georgius Agricola

Etymology

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

From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites

Class

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Glassy

Glassy, Massive, Porphyritic, Scoriaceous, Vesicular

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

Floor Tiles, Homes, Hotels, Kitchens

Exterior Uses

Garden Decoration

As Building Stone, Paving Stone, Garden Decoration, Office Buildings

Other Architectural Uses

Curbing, Whetstones

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Arrowheads, As Dimension Stone, Cobblestones, Cutting Tool, Rail Track Ballast, Roadstone

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Monuments

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

An Oil and Gas Reservoir, Commemorative Tablets, Creating Artwork, Used in aquariums

Types

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

Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite

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

Easter Island in the Polynesian Triangle, Pacific Ocean, Gateway of India in Mumbai, India, Gol Gumbaz in Karnataka, India

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.

Basalt forms when lava reaches the Earth's surface near an active volcano. The temperature of lava is between 1100 to 1250° C when it gets to the surface.

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact 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

Properties

Physical Properties

Hardness

5-5.56

1 7

👆🏻

Grain Size

Fine Grained

Fracture

Conchoidal

Streak

White

White to Grey

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Compressive Strength

0.15 N/mm²37.40 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

2.3

Specific Gravity

2.6-2.72.8-3

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³2.9-3.1 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

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 Basalt Properties

Know all about Obsidian and Basalt properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Basalt belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Basalt is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Obsidian appears Shiny and Basalt appears Dull and Soft. The luster of Obsidian is vitreous while that of Basalt is . Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Basalt 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 Basalt are an oil and gas reservoir, commemorative tablets, creating artwork, used in aquariums.