Tuff

Picrite

Tuff and Picrite

Tuff

Picrite

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Definition

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

Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine

History

Origin

Italy

Hawaii Islands

Discoverer

Unknown

Etymology

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

From Greek pikros bitter + -ite, 19th century

Class

Igneous 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

Earthy, Rough

Color

Brown, Grey, Yellow

Black, Brown, Green, Grey, Pink, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull, Vesicular and Foilated

Rough and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration

Countertops, Decorative Aggregates, Homes, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

Building houses or walls, Construction Aggregate

As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Creating Artwork

As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)

Types

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

Oceanite

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.

Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

Composition

Mineral Content

Calcite, Chlorite

Biotite, Olivine, Plagioclase, Pyrrhotite

Compound Content

Hydrogen Sulfide, Sulfur Dioxide

Al, CaO, Carbon Dioxide, Mg, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering

Erosion

✔ ✘

Types of Erosion

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

Properties

Physical Properties

Hardness

4-66.8

1 7

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Grain Size

Fine Grained

Fracture

Uneven

Streak

White

White, Greenish White or Grey

Porosity

Highly Porous

Less Porous

Luster

Vitreous to Dull

Subvitreous to Dull

Compressive Strength

243.80 N/mm²189.00 N/mm²

0.15 450

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Cleavage

Toughness

2.1

Specific Gravity

2.732.75-2.92

0 8.4

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Transparency

Opaque

Density

1-1.8 g/cm³1.5-2.5 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.20 kJ/Kg K0.88 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

India, Russia

Africa

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

South Africa

Europe

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

Iceland

Others

Antarctica, Hawaii Islands

Deposits in Western Continents

North America

Canada, Costa Rica, Panama, USA

Canada, USA

South America

Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay

Brazil

Deposits in Oceania Continent

Australia

Central Australia, Western Australia

All about Tuff and Picrite Properties

Know all about Tuff and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Tuff and Picrite belong to Igneous Rocks.Texture of Tuff is Clastic, Pyroclastic whereas that of Picrite is Earthy, Rough. Tuff appears Dull, Vesicular and Foilated and Picrite appears Rough and Shiny. The luster of Tuff is vitreous to dull while that of Picrite is subvitreous to dull. Tuff is available in brown, grey, yellow colors whereas Picrite is available in black, brown, green, grey, pink, white, yellow colors. The commercial uses of Tuff are creating artwork and that of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).