Tuff

Pseudotachylite

Tuff and Pseudotachylite

Tuff

Pseudotachylite

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Definition

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

Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.

History

Origin

Italy

USA

Discoverer

Unknown

Etymology

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

From pseudo- +‎ tachylite, a glassy rock generated by frictional heat within faults.

Class

Igneous Rocks

Metamorphic Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Clastic, Pyroclastic

Quench

Color

Brown, Grey, Yellow

Black, Brown, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull, Vesicular and Foilated

Dull and Soft

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

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

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Building houses or walls, Construction Aggregate

As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Monuments

Other Uses

Commercial Uses

Creating Artwork

Creating Artwork, Gemstone

Types

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

Cataclastic rock

Features

Always found as volcanic pipes over deep continental crust

Host Rock for Lead

Archaeological Significance

Monuments

Famous Monuments

Easter Island in the Polynesian Triangle, Pacific Ocean

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.

Composition

Mineral Content

Calcite, Chlorite

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Compound Content

Hydrogen Sulfide, Sulfur Dioxide

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact 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, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

4-67

1 7

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Grain Size

Fine Grained

Very fine-grained

Fracture

Uneven

Streak

White

Light to dark brown

Porosity

Highly Porous

Less Porous

Luster

Vitreous to Dull

Vitreous

Compressive Strength

243.80 N/mm²60.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.732.46-2.86

0 8.4

👆🏻

Transparency

Opaque

Transparent to Translucent

Density

1-1.8 g/cm³2.7-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.20 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

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

South Korea

Africa

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

Western Africa

Europe

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

Great Britain, Switzerland

Others

Antarctica, Hawaii Islands

Deposits in Western Continents

North America

Canada, Costa Rica, Panama, USA

South America

Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay

Deposits in Oceania Continent

Australia

Central Australia, Western Australia

All about Tuff and Pseudotachylite Properties

Know all about Tuff and Pseudotachylite properties here. All properties of rocks are important as they define the type of rock and its application. Tuff belongs to Igneous Rocks while Pseudotachylite belongs to Metamorphic Rocks.Texture of Tuff is Clastic, Pyroclastic whereas that of Pseudotachylite is Quench. Tuff appears Dull, Vesicular and Foilated and Pseudotachylite appears Dull and Soft. The luster of Tuff is vitreous to dull while that of Pseudotachylite is vitreous. Tuff is available in brown, grey, yellow colors whereas Pseudotachylite is available in black, brown, green, grey, pink, white colors. The commercial uses of Tuff are creating artwork and that of Pseudotachylite are creating artwork, gemstone.