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What is Gneiss?



Definition

Definition
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
-

Discoverer
Unknown

Etymology
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
Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Texture
Banded, Foliated, Platy

Color
Black, Brown, Pink, Red, White

Maintenance
More

Durability
Durable

Water Resistant
Yes

Scratch Resistant
Yes

Stain Resistant
Yes

Wind Resistant
Yes

Acid Resistant
No

Appearance
Foliated

Uses

Architecture

Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration

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

Other Architectural Uses
Curbing

Industry

Construction Industry
As Dimension Stone

Medical Industry
-

Antiquity Uses
Artifacts

Other Uses

Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Types

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

Features
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

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

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

Transformation

Metamorphism
Yes

Types of Metamorphism
Impact Metamorphism

Weathering
Yes

Types of Weathering
Biological Weathering, Mechanical Weathering

Erosion
Yes

Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion

Properties

Physical Properties

Hardness
7

Grain Size
Medium to Coarse Grained

Fracture
Irregular

Streak
White

Porosity
Very Less Porous

Luster
Dull

Compressive Strength
125.00 N/mm2 25

Cleavage
-

Toughness
1.2

Specific Gravity
2.5-2.7

Transparency
Translucent to Opaque

Density
2.6-2.9 g/cm3

Thermal Properties

Specific Heat Capacity
0.70 kJ/Kg K 24

Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

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

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

Europe
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
New South Wales, New Zealand, Queensland, Victoria

Summary >>
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Metamorphic Rocks

Learn more about Properties of Gneiss

What is Gneiss? In this section, we will learn more about properties of Gneiss i.e. physical and thermal properties. Physical properties of Gneiss include Color, Streak, Hardness, Structure, Cleavage, Fracture, Luster, Specific Gravity etc. The strength of Gneiss is 125.00 N/mm2. Streak of Gneiss is white while its cleavage is . Luster of Gneiss is dull and its fracture is irregular. Gneiss is translucent to opaque in nature. Know all about Gneiss, What is Gneiss, its composition, features, facts and reserves in next sections.

Know about Composition of Gneiss

What is Gneiss composed of? Get to know about composition of Gneiss here. Gneiss definition gives information about the Formation of Gneiss and its composition.The composition of Gneiss can be further divided into mineral and compound content. The mineral content of Gneiss rock includes Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon and The compound content of Gneiss rock includes Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide. Almost all rocks undergo transformation process. Know all about Gneiss rock in next section.

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