Chert

Obsidian

Chert and Obsidian

Chert

Obsidian

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1 Definition

1.1 Definition

Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture

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

1.2 History

1.2.1 Origin

Unknown

Ethiopia

1.2.2 Discoverer

Unknown

Obsius

1.3 Etymology

From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use

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

1.4 Class

Sedimentary Rocks

Igneous Rocks

1.4.1 Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

1.5 Family

1.5.1 Group

Not Applicable

Volcanic

1.6 Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

2 Texture

2.1 Texture

Banded, Rough

Glassy

2.2 Color

Black, Brown, Green, Grey, Red, White

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

2.3 Maintenance

Less

2.4 Durability

Durable

2.4.1 Water Resistant

✔ ✘

59% Sedimentary Rocks Rocks have it !

✔ ✘

81% Igneous Rocks Rocks have it !

2.4.2 Scratch Resistant

✔ ✘

62% Sedimentary Rocks Rocks have it !

✔ ✘

86% Igneous Rocks Rocks have it !

2.4.3 Stain Resistant

✔ ✘

43% Sedimentary Rocks Rocks have it !

✔ ✘

66% Igneous Rocks Rocks have it !

2.4.4 Wind Resistant

✔ ✘

38% Sedimentary Rocks Rocks have it !

✔ ✘

49% Igneous Rocks Rocks have it !

2.4.5 Acid Resistant

✔ ✘

22% Sedimentary Rocks Rocks have it !

✔ ✘

48% Igneous Rocks Rocks have it !

2.5 Appearance

Glassy or Pearly

Shiny

3 Uses

3.1 Architecture

3.1.1 Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Interior Decoration

3.1.2 Exterior Uses

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

Garden Decoration

3.1.3 Other Architectural Uses

Curbing

Not Yet Used

3.2 Industry

3.2.1 Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

3.2.2 Medical Industry

Not Yet Used

Surgery

3.3 Antiquity Uses

Artifacts, Monuments

Artifacts, Jewellery

3.4 Other Uses

3.4.1 Commercial Uses

Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms

Creating Artwork, Mirror, Used in aquariums

4 Types

4.1 Types

Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter

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

4.2 Features

Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate

Blocks negativity, Helps to protect against depression

4.3 Archaeological Significance

4.3.1 Monuments

Used

Not Yet Used

4.3.2 Famous Monuments

Data Not Available

Not Applicable

4.3.3 Sculpture

Not Yet Used

4.3.4 Famous Sculptures

Not Applicable

4.3.5 Pictographs

Not Used

Used

4.3.6 Petroglyphs

Not Used

Used

4.3.7 Figurines

Not Yet Used

4.4 Fossils

Present

Absent

5 Formation

5.1 Formation

Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.

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.

5.2 Composition

5.2.1 Mineral Content

Quartz, Silicon

Not Available

5.2.2 Compound Content

Silicon Dioxide

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

5.3 Transformation

5.3.1 Metamorphism

✔ ✘

19% Sedimentary Rocks Rocks have it !

✔ ✘

97% Igneous Rocks Rocks have it !

5.3.2 Types of Metamorphism

Not Applicable

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

5.3.3 Weathering

✔ ✘

78% Sedimentary Rocks Rocks have it !

✔ ✘

99% Igneous Rocks Rocks have it !

5.3.4 Types of Weathering

Not Applicable

Biological Weathering, Chemical Weathering, Mechanical Weathering

5.3.5 Erosion

✔ ✘

86% Sedimentary Rocks Rocks have it !

✔ ✘

92% Igneous Rocks Rocks have it !

5.3.6 Types of Erosion

Chemical Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

6 Properties

6.1 Physical Properties

6.1.1 Hardness

6.5-7

5-5.5

6.1.2 Grain Size

Very fine-grained

Not Applicable

6.1.3 Fracture

Uneven, Splintery or Conchoidal

Conchoidal

6.1.4 Streak

White

6.1.5 Porosity

Highly Porous

Very Less Porous

6.1.6 Luster

Waxy and Dull

Vitreous

6.1.7 Compressive Strength

What Is Flint

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▶

▼

450.00 N/mm²

Rank: 1 (Overall)▶

0.15 N/mm²

Rank: 33 (Overall)▶

▲

What Is Obsidian

⊕

▶

175 (What Is Grani..)

◀ ▶ ADD ⊕

6.1.8 Cleavage

Non-Existent

6.1.9 Toughness

1.5

Not Available

6.1.10 Specific Gravity

2.5-2.8

2.6-2.7

6.1.11 Transparency

Translucent to Opaque

Translucent

6.1.12 Density

2.7 g/cm³

2.6 g/cm³

6.2 Thermal Properties

6.2.1 Specific Heat Capacity

What Is Banded ..

⊕

▶

▼

0.74 kJ/Kg K

Rank: 19 (Overall)▶

0.92 kJ/Kg K

Rank: 10 (Overall)▶

▲

What Is Granulite

⊕

▶

1.09 (What Is Trave..)

◀ ▶ ADD ⊕

6.2.2 Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant, Impact Resistant

7 Reserves

7.1 Deposits in Eastern Continents

7.1.1 Asia

China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam

Afghanistan, Indonesia, Japan, Russia

7.1.2 Africa

Kenya, Morocco, South Africa, Tanzania

Kenya

7.1.3 Europe

Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom

Greece, Hungary, Iceland, Italy, Turkey

7.1.4 Others

Greenland, Mid-Atlantic Ridge

Not Yet Found

7.2 Deposits in Western Continents

7.2.1 North America

Canada, Mexico, USA

7.2.2 South America

Bolivia, Brazil

Argentina, Chile, Ecuador, Peru

7.3 Deposits in Oceania Continent

7.3.1 Australia

New South Wales, Queensland, South Australia, Western Australia

New Zealand

All about Chert and Obsidian Properties

Know all about Chert and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Obsidian belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Obsidian is Glassy. Chert appears Glassy or Pearly and Obsidian appears Shiny. The luster of Chert is waxy and dull while that of Obsidian is vitreous. Chert is available in black, brown, green, grey, red, white colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms and that of Obsidian are creating artwork, mirror, used in aquariums.