Pseudotachylite

Gneiss

Pseudotachylite and Gneiss

Pseudotachylite

Gneiss

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Definition

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

Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks

History

Origin

USA

Discoverer

Unknown

Etymology

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

From the Middle High German verb gneist (to spark; so called because the rock glitters)

Class

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Quench

Banded, Foliated, Platy

Color

Black, Brown, Green, Grey, Pink, White

Black, Brown, Pink, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull and Soft

Foliated

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Countertops, Decorative Aggregates, Flooring, Interior Decoration

Exterior Uses

As Building Stone, As Facing Stone, Garden Decoration

As Building Stone, As Facing Stone, 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

Medical Industry

Antiquity Uses

Artifacts, Monuments

Artifacts

Other Uses

Commercial Uses

Creating Artwork, Gemstone

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Types

Cataclastic rock

Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.

Features

Host Rock for Lead

Generally rough to touch, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Konark Sun Temple in India, Washington Monument, US

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.

Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.

Composition

Mineral Content

Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides

Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon

Compound Content

Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur

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

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Impact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Properties

Physical Properties

Hardness

1 7

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Grain Size

Very fine-grained

Medium to Coarse Grained

Fracture

Uneven

Irregular

Streak

Light to dark brown

White

Porosity

Less Porous

Very Less Porous

Luster

Vitreous

Dull

Compressive Strength

60.00 N/mm²125.00 N/mm²

0.15 450

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Cleavage

Toughness

1.2

Specific Gravity

2.46-2.862.5-2.7

0 8.4

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Transparency

Transparent to Translucent

Translucent to Opaque

Density

2.7-2.9 g/cm³2.6-2.9 g/cm³

0 1400

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Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.70 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

South Korea

China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia

Africa

Western Africa

Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo

Europe

Great Britain, Switzerland

Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom

Others

Deposits in Western Continents

North America

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

South America

Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

Central Australia, Western Australia

New South Wales, New Zealand, Queensland, Victoria

All about Pseudotachylite and Gneiss Properties

Know all about Pseudotachylite and Gneiss properties here. All properties of rocks are important as they define the type of rock and its application. Pseudotachylite and Gneiss belong to Metamorphic Rocks.Texture of Pseudotachylite is Quench whereas that of Gneiss is Banded, Foliated, Platy. Pseudotachylite appears Dull and Soft and Gneiss appears Foliated. The luster of Pseudotachylite is vitreous while that of Gneiss is dull. Pseudotachylite is available in black, brown, green, grey, pink, white colors whereas Gneiss is available in black, brown, pink, red, white colors. The commercial uses of Pseudotachylite are creating artwork, gemstone and that of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums.