Gneiss

Skarn

Gneiss and Skarn

Gneiss

Skarn

Add ⊕

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

Skarns are formed during regional or contact metamorphism and from a variety of metasomatic processes involving fluids of magmatic, metamorphic, and/or marine origin

History

Origin

USA, Australia

Discoverer

Unknown

Tornebohm

Etymology

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

From an old Swedish mining term originally used to describe a type of silicate gangue or waste rock.

Class

Metamorphic Rocks

Sub-Class

Durable Rock, Hard Rock

Family

Group

Other Categories

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Banded, Foliated, Platy

Earthy, Mud-rich, Rough

Color

Black, Brown, Pink, Red, White

Black, Brown, Green, Grey, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Foliated

Dull

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Flooring, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

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

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone

As a Flux in the Production of Steel and Pig Iron, As a Sintering Agent in Steel Industry to process Iron Ore, As Dimension Stone, Gold and Silver production, Manufacture of Magnesium and Dolomite Refractories

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments, Sculpture

Other Uses

Commercial Uses

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Creating Artwork, Gemstone, Jewelry, Metallurgical Flux, Source of Magnesia (MgO)

Types

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

Endoskarns

Features

Generally rough to touch, Is one of the oldest rock

Host Rock for Lead, Zinc and Copper Deposits

Archaeological Significance

Monuments

Famous Monuments

Konark Sun Temple in India, Washington Monument, US

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

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

Composition

Mineral Content

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

Calcite, Enstatite, Epidote, Garnet, Magnetite, Pyroxene, Titanite

Compound Content

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

Au, CaO, Carbon Dioxide, Cu, Fe, MgO

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Impact Metamorphism

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

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Properties

Physical Properties

Hardness

76.5

1 7

👆🏻

Grain Size

Medium to Coarse Grained

Fine Grained

Fracture

Irregular

Streak

White

Light to dark brown

Porosity

Very Less Porous

Less Porous

Luster

Dull

Waxy and Dull

Compressive Strength

125.00 N/mm²70.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.2

2.4

Specific Gravity

2.5-2.72.86

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.6-2.9 g/cm³2.8-2.9 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.70 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Russia, Saudi Arabia, South Korea, Sri Lanka

Africa

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

South Africa, Western Africa

Europe

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

United Kingdom

Others

Deposits in Western Continents

North America

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

Canada

South America

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

Brazil, Colombia, Paraguay

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Victoria

Central Australia, Western Australia

All about Gneiss and Skarn Properties

Know all about Gneiss and Skarn properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss and Skarn belong to Metamorphic Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Skarn is Earthy, Mud-rich, Rough. Gneiss appears Foliated and Skarn appears Dull. The luster of Gneiss is dull while that of Skarn is waxy and dull. Gneiss is available in black, brown, pink, red, white colors whereas Skarn is available in black, brown, green, grey, white colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Skarn are creating artwork, gemstone, jewelry, metallurgical flux, source of magnesia (mgo).