Coal

Obsidian

Coal and Obsidian

Coal

Obsidian

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Definition

Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds

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

USA

Ethiopia

Discoverer

John Peter Salley

Obsius

Etymology

From the Old English term col, which has meant mineral of fossilized carbon since the 13th century

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

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Opaque Rock

Texture

Amorphous, Glassy

Glassy

Color

Black, Brown, Dark Brown, Grey, Light to Dark Grey

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Veined or Pebbled

Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Exterior Uses

Garden Decoration

Other Architectural Uses

Industry

Construction Industry

Cement Manufacture, for Road Aggregate, Making natural cement, Steel Production

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts

Artifacts, Jewellery

Other Uses

Commercial Uses

Alumina Refineries, Electricity Generation, Liquid Fuel, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Paper Industry

Creating Artwork, Mirror, Used in aquariums

Types

Peat, Lignite, Sub-Bituminous Coal, Bituminous Coal, Anthracite, Graphite

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

Features

Helps in production of Heat and Electricity, Used as fossil fuel

Blocks negativity, Helps to protect against depression

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

Coal forms from the accumulation of plant debris in a swamp environment which is buried by sediments such as mud or sand and then compacted to form coal.

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

Analcime, Apatite, Barite, Calcite, Chalcopyrite, Chlorite, Chromite, Clausthalite, Clay Minerals, Crandallite Group, Dolomite, Feldspar, Galena, Gypsum, Marcasite, Muscovite or Illite, Pyrite, Quartz, Siderite, Sphalerite, Zircon

Compound Content

Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur

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, Regional Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact 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

1-1.55-5.5

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fracture

Conchoidal

Streak

Black

White

Porosity

Less Porous

Very Less Porous

Luster

Dull to Vitreous to Submetallic

Vitreous

Compressive Strength

-0.15 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

1.1-1.42.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

1100-1400 g/cm³2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

1.32 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

Bangladesh, Burma, Cambodia, China, India, Indonesia, Kazakhstan, Malaysia, Mongolia, Pakistan, Turkey, Vietnam

Afghanistan, Indonesia, Japan, Russia

Africa

Botswana, Kenya, Morocco, Mozambique, South Africa, Tanzania

Kenya

Europe

Belgium, Bulgaria, England, France, Germany, Greece, Hungary, Kosovo, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, The Czech Republic, Ukraine, United Kingdom

Greece, Hungary, Iceland, Italy, Turkey

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

South America

Brazil, Chile, Colombia, Venezuela

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

New South Wales, Queensland, Victoria

New Zealand

All about Coal and Obsidian Properties

Know all about Coal and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Coal belongs to Sedimentary Rocks while Obsidian belongs to Igneous Rocks.Texture of Coal is Amorphous, Glassy whereas that of Obsidian is Glassy. Coal appears Veined or Pebbled and Obsidian appears Shiny. The luster of Coal is dull to vitreous to submetallic while that of Obsidian is vitreous. Coal is available in black, brown, dark brown, grey, light to dark grey colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Coal are alumina refineries, electricity generation, liquid fuel, manufacture of soap, solvents, dyes, plastics and fibres, paper industry and that of Obsidian are creating artwork, mirror, used in aquariums.