Obsidian

Lignite

Obsidian and Lignite

Obsidian

Lignite

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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

Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat

History

Origin

Ethiopia

France

Discoverer

Obsius

Unknown

Etymology

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

From French, Latin lignum wood + -ite1

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Soft Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

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

Texture

Glassy

Amorphous, Glassy

Color

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

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

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Veined or Pebbled

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Exterior Uses

Garden Decoration

Other Architectural Uses

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

for Road Aggregate, Steel Production

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

Electricity Generation

Types

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

Xyloid Lignite or Fossil Wood and Compact Lignite or Perfect Lignite

Features

Blocks negativity, Helps to protect against depression

Generally rough to touch, Helps in production of Heat and Electricity, Used as fossil fuel

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

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.

Coal formation takes place due to accumulation of plant debris in a swamp environment. The Coal formation process continues, as peat turns into lignite brown or black coal at increasing heat and pressure.

Composition

Mineral Content

Compound Content

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

Carbon, Hydrogen, Nitrogen, Oxygen, Sulphur

Transformation

Metamorphism

✔ ✘

Types of 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

Chemical Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

5-5.51

1 7

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Grain Size

Medium to Fine Coarse Grained

Fracture

Conchoidal

Streak

White

Black

Porosity

Very Less Porous

Highly Porous

Luster

Vitreous

Dull to Vitreous to Submetallic

Compressive Strength

0.15 N/mm²-

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.6-2.71.1-1.4

0 8.4

👆🏻

Transparency

Translucent

Opaque

Density

2.6 g/cm³800-801 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K1.26 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

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

Africa

Kenya

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

Europe

Greece, Hungary, Iceland, Italy, Turkey

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

Others

Deposits in Western Continents

North America

Canada, Mexico, USA

South America

Argentina, Chile, Ecuador, Peru

Brazil, Chile, Colombia, Venezuela

Deposits in Oceania Continent

Australia

New Zealand

New South Wales, Queensland, Victoria

All about Obsidian and Lignite Properties

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