Pseudotachylite

Schist

Pseudotachylite and Schist

Pseudotachylite

Schist

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Definition

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

Schist is a medium grade metamorphic rock with medium to large, flat, sheet like grains in a preferred orientation

History

Origin

USA

Discoverer

Unknown

Etymology

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

From French schiste, Greek skhistos i.e. split

Class

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Quench

Foliated, Platy

Color

Black, Brown, Green, Grey, Pink, White

Black, Blue, Brown, Dark Brown, Green, Grey, Silver

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Soft

Layered and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Decorative Aggregates, Floor Tiles, Interior Decoration

Exterior Uses

As Building Stone, As Facing Stone, Garden Decoration

Garden Decoration, Paving Stone

Other Architectural Uses

Curbing

Industry

Construction Industry

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

As Dimension Stone, Building houses or walls, Cement Manufacture, for Road Aggregate, Roadstone

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts

Other Uses

Commercial Uses

Creating Artwork, Gemstone

Used in aquariums, Writing Slates

Types

Cataclastic rock

Mica Schists, Calc-Silicate Schists, Graphite Schists, Blueschists, Whiteschists, Greenschists, Hornblende Schist, Talc Schist, Chlorite Schist, Garnet Schist, Glaucophane schist.

Features

Host Rock for Lead

Easily splits into thin plates, Smooth to touch

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

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.

Schist formed by dynamic metamorphism at high temperatures and pressures that aligns the grains of mica, hornblende and other elongated minerals into thin layers.

Composition

Mineral Content

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc

Compound Content

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

CaO, Carbon Dioxide, MgO

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

Properties

Physical Properties

Hardness

73.5-4

1 7

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Grain Size

Very fine-grained

Medium to Fine Coarse Grained

Fracture

Uneven

Conchoidal

Streak

Light to dark brown

White

Porosity

Less Porous

Highly Porous

Luster

Vitreous

Shiny

Compressive Strength

60.00 N/mm²150.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.5

Specific Gravity

2.46-2.862.5-2.9

0 8.4

👆🏻

Transparency

Transparent to Translucent

Opaque

Density

2.7-2.9 g/cm³2.8-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.70 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Impact Resistant, Pressure Resistant, Water Resistant

Reserves

Deposits in Eastern Continents

Asia

South Korea

Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam

Africa

Western Africa

Egypt, Ethiopia, Morocco, Nigeria, South Africa

Europe

Great Britain, Switzerland

Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland

Others

Deposits in Western Continents

North America

Canada, Costa Rica, Cuba, Mexico, Panama, USA

South America

Brazil, Colombia, Guyana

Deposits in Oceania Continent

Australia

Central Australia, Western Australia

New South Wales, New Zealand, Queensland

All about Pseudotachylite and Schist Properties

Know all about Pseudotachylite and Schist properties here. All properties of rocks are important as they define the type of rock and its application. Pseudotachylite and Schist belong to Metamorphic Rocks.Texture of Pseudotachylite is Quench whereas that of Schist is Foliated, Platy. Pseudotachylite appears Dull and Soft and Schist appears Layered and Shiny. The luster of Pseudotachylite is vitreous while that of Schist is shiny. Pseudotachylite is available in black, brown, green, grey, pink, white colors whereas Schist is available in black, blue, brown, dark brown, green, grey, silver colors. The commercial uses of Pseudotachylite are creating artwork, gemstone and that of Schist are used in aquariums, writing slates.