Chert and Tuff

Chert

Tuff

Tuff and Chert

Definition

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

Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption

History

Origin

Unknown

Italy

Discoverer

Unknown

Etymology

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

From a Latin word tophous then in Italian tufo and finally tuff

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Not Applicable

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Banded, Rough

Clastic, Pyroclastic

Color

Black, Brown, Green, Grey, Red, White

Brown, Grey, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

Yes

Scratch Resistant

Yes

Stain Resistant

Yes

Wind Resistant

Acid Resistant

Yes

Appearance

Glassy or Pearly

Dull, Vesicular and Foilated

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes

Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Building houses or walls, Construction Aggregate

Medical Industry

Not Yet Used

Antiquity Uses

Artifacts, Monuments

Artifacts, Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

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

Creating Artwork

Types

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

Welded tuff, Rhyolitic tuff, Basaltic tuff, Trachyte tuff, Andesitic tuff and Ignimbrite.

Features

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

Always found as volcanic pipes over deep continental crust

Archaeological Significance

Monuments

Used

Famous Monuments

Data Not Available

Easter Island in the Polynesian Triangle, Pacific Ocean

Sculpture

Not Yet Used

Used

Famous Sculptures

Not Applicable

Data Not Available

Pictographs

Not Used

Used

Petroglyphs

Not Used

Used

Figurines

Not Yet Used

Used

Fossils

Present

Absent

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.

Tuff is formed when large masses of ash and sand which are mixed with hot gases are ejected by a volcano and avalanche rapidly down its slopes.

Composition

Mineral Content

Quartz, Silicon

Calcite, Chlorite

Compound Content

Silicon Dioxide

Hydrogen Sulfide, Sulfur Dioxide

Transformation

Metamorphism

Yes

Types of Metamorphism

Not Applicable

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

Yes

Types of Weathering

Not Applicable

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

Yes

Types of Erosion

Chemical Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

6.5-7

4-6

Grain Size

Very fine-grained

Fine Grained

Fracture

Uneven, Splintery or Conchoidal

Uneven

Streak

White

Porosity

Highly Porous

Luster

Waxy and Dull

Vitreous to Dull

Compressive Strength

450.00 N/mm²

243.80 N/mm²

Cleavage

Non-Existent

Not Available

Toughness

1.5

Not Available

Specific Gravity

2.5-2.8

2.73

Transparency

Translucent to Opaque

Opaque

Density

2.7 g/cm³

1-1.8 g/cm³

Thermal Properties

Specific Heat Capacity

0.74 kJ/Kg K

0.20 kJ/Kg K

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Afghanistan, Armenia, Azerbaijan, Burma, Cambodia, China, India, Indonesia, Iran, Japan, Malaysia, Mongolia, Nepal, North Korea, Pakistan, Saudi Arabia, Syria, Taiwan, Thailand, Turkey, Vietnam, Yemen

Africa

Kenya, Morocco, South Africa, Tanzania

Cameroon, Cape Verde, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Uganda

Europe

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

France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom

Others

Greenland, Mid-Atlantic Ridge

Antarctica, Hawaii Islands

Deposits in Western Continents

North America

Canada, Mexico, USA

Canada, Costa Rica, Panama, USA

South America

Bolivia, Brazil

Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay

Deposits in Oceania Continent

Australia

New South Wales, Queensland, South Australia, Western Australia

Central Australia, Western Australia

Summary >>

<< Reserves

All about Chert and Tuff Properties

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