Obsidian

Amphibolite

Obsidian and Amphibolite

Obsidian

Amphibolite

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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

Amphibolite can be defined as a granular metamorphic rock which mainly consist of hornblende and plagioclase

History

Origin

Ethiopia

Discoverer

Obsius

Alexandre Brongniart

Etymology

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

From Amphibole + -ite

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Glassy

Banded, Foliated, Massive

Color

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

Black, Brown, Green, Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Foliated

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Kitchens

Exterior Uses

Garden Decoration

As Building Stone, As Facing Stone, Paving Stone, Office Buildings

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

As Dimension Stone, Building houses or walls, Cobblestones, Construction Aggregate, for Road Aggregate, Landscaping, Production of Glass and Ceramics, Roadstone

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Cemetery Markers, Commemorative Tablets, Creating Artwork

Types

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

Hornblendite

Features

Blocks negativity, Helps to protect against depression

Clasts are smooth to touch, Matrix variable, Surfaces are often shiny

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.

Amphibolite is a coarse-grained metamorphic rock which forms by metamorphism of mafic igneous rocks like basalt and gabbro or from the metamorphism of clay-rich sedimentary rocks like marl or graywacke.

Composition

Mineral Content

Amphibole, Andalusite, Biotite, Calcite, Epidote, Garnet, Hornblade, Kyanite, Magnetite, Olivine, Plagioclase, Pyroxene, Staurolite, Wollastonite

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

Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Glacier Erosion, Sea Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.56-7

1 7

👆🏻

Grain Size

Medium to Coarse Grained

Fracture

Conchoidal

Irregular to Conchoidal

Streak

White

White to Grey

Porosity

Very Less Porous

Less Porous

Luster

Vitreous

Vitreous to Dull

Compressive Strength

0.15 N/mm²90.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

2.3

Specific Gravity

2.6-2.72.5

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³2.85-3.07 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

Russia, Turkey

Africa

Kenya

Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Rwanda, Somalia, South Africa, Sudan, Tanzania, Uganda

Europe

Greece, Hungary, Iceland, Italy, Turkey

Germany, Greece, Iceland, Norway, Poland

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

South Australia, Western Australia

All about Obsidian and Amphibolite Properties

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