Obsidian

Variolite

Obsidian and Variolite

Obsidian

Variolite

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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

Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance

History

Origin

Ethiopia

France

Discoverer

Obsius

Unknown

Etymology

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

From Latin varius, speckled, variegated

Class

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

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, Flooring, Homes, Hotels, Kitchens

Exterior Uses

Garden Decoration

Garden Decoration, Office Buildings

Other Architectural Uses

Curbing

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, Creating Artwork

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.

Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.

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

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

1 7

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Grain Size

Fracture

Conchoidal

Streak

White

White to Grey

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Compressive Strength

0.15 N/mm²37.50 N/mm²

0.15 450

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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 Variolite Properties

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