Obsidian

Chert

Obsidian vs Chert

Obsidian

Chert

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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

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

History

Origin

Ethiopia

Discoverer

Obsius

Unknown

Etymology

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

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

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Glassy

Banded, Rough

Color

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

Black, Brown, Green, Grey, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Shiny

Glassy or Pearly

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Homes

Exterior Uses

Garden Decoration

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Jewellery

Artifacts, Monuments

Other Uses

Commercial Uses

Creating Artwork, Mirror, Used in aquariums

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

Types

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

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

Features

Blocks negativity, Helps to protect against depression

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

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.

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.

Composition

Mineral Content

Quartz, Silicon

Compound Content

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

Silicon Dioxide

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

Properties

Physical Properties

Hardness

5-5.56.5-7

1 7

👆🏻

Grain Size

Very fine-grained

Fracture

Conchoidal

Uneven, Splintery or Conchoidal

Streak

White

Porosity

Very Less Porous

Highly Porous

Luster

Vitreous

Waxy and Dull

Compressive Strength

0.15 N/mm²450.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.5

Specific Gravity

2.6-2.72.5-2.8

0 8.4

👆🏻

Transparency

Translucent

Translucent to Opaque

Density

2.6 g/cm³2.7 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.74 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Indonesia, Japan, Russia

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

Africa

Kenya

Kenya, Morocco, South Africa, Tanzania

Europe

Greece, Hungary, Iceland, Italy, Turkey

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

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

Canada, Mexico, USA

South America

Argentina, Chile, Ecuador, Peru

Bolivia, Brazil

Deposits in Oceania Continent

Australia

New Zealand

New South Wales, Queensland, South Australia, Western Australia

Obsidian vs Chert Information

Earth’s outer layer is covered by rocks and these rocks have different physical and chemical properties. As two rocks are not same, it’s fun to compare them. You can also know more about Obsidian and Chert Reserves. 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. Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture. These rocks are composed of many distinct minerals. The process of formation of rocks is different for various rocks. Rocks are quarried from many years for various purposes. You can check out Obsidian vs Chert information and Obsidian vs Chert characteristics in the upcoming sections.

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Obsidian vs Chert Characteristics

Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Obsidian vs Chert characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Obsidian and Properties of Chert. Learn more about Obsidian vs Chert in the next section. The interior uses of Obsidian include Decorative aggregates and Interior decoration whereas the interior uses of Chert include Decorative aggregates and Homes. Due to some exceptional properties of Obsidian and Chert, they have various applications in construction industry. The uses of Obsidian in construction industry include Arrowheads, Cutting tool, Knives, Scrapers, Spear points and that of Chert include Arrowheads, Construction aggregate, Cutting tool, Spear points.

More about Obsidian and Chert

Here you can know more about Obsidian and Chert. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Obsidian and Chert consists of mineral content and compound content. The mineral content of Obsidian includes and mineral content of Chert includes Quartz, Silicon. You can also check out the list of all Igneous Rocks. When we have to compare Obsidian vs Chert, the texture, color and appearance plays an important role in determining the type of rock. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas, Chert is available in black, brown, green, grey, red, white colors. Appearance of Obsidian is Shiny and that of Chert is Glassy or Pearly. Properties of rock is another aspect for Obsidian vs Chert. The hardness of Obsidian is 5-5.5 and that of Chert is 6.5-7. The types of Obsidian are Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian whereas types of Chert are Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Obsidian and Chert is white. The specific heat capacity of Obsidian is 0.92 kJ/Kg K and that of Chert is 0.74 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Obsidian is heat resistant, impact resistant whereas Chert is heat resistant, impact resistant, pressure resistant, wear resistant.