Gneiss

Adakite

Gneiss and Adakite

Gneiss

Adakite

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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

Adakite is an intermediate to felsic volcanic rock that has geochemical characteristics of magma which is said to be formed by partial melting of altered basalt that is subducted below volcanic arcs

History

Origin

Adak, Aleutian Islands

Discoverer

Unknown

Defant and Drummond

Etymology

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

From Adak, Aleutian Islands

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Banded, Foliated, Platy

Porphyritic

Color

Black, Brown, Pink, Red, White

Black, Brown, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Foliated

Dull and Soft

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Flooring, Interior Decoration

Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens

Exterior Uses

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

As Building Stone, As Facing Stone, Office Buildings

Other Architectural Uses

Curbing

Whetstones

Industry

Construction Industry

As Dimension Stone

As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone

Medical Industry

Antiquity Uses

Artifacts

Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Commemorative Tablets, Pottery, Used in aquariums

Types

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

Intermediate volcanic rock

Features

Generally rough to touch, Is one of the oldest rock

Has High structural resistance against erosion and climate, Host rock for Diamond, Very fine grained rock

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.

Adakite rocks are formed when the hydrous fluids are released from minerals that break down in metamorphosed basalt, and rise into the mantle they initiate partial melting.

Composition

Mineral Content

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

Olivine, Plagioclase, Pyroxene

Compound Content

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

Aluminium Oxide, MgO, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Impact Metamorphism

Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Mechanical Weathering

Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Coastal Erosion, Sea Erosion, Water Erosion

Properties

Physical Properties

Hardness

73-4

1 7

👆🏻

Grain Size

Medium to Coarse Grained

Fine to Medium Grained

Fracture

Irregular

Conchoidal

Streak

White

Bluish Black

Porosity

Very Less Porous

Less Porous

Luster

Dull

Grainy, Pearly and Vitreous

Compressive Strength

125.00 N/mm²200.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.2

Specific Gravity

2.5-2.7-9999

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.6-2.9 g/cm³-9999 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.70 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Heat Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

India, Russia

Africa

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

Ethiopia, Somalia, South 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

Iceland

Others

Deposits in Western Continents

North America

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

Canada, USA

South America

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

Brazil

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Victoria

All about Gneiss and Adakite Properties

Know all about Gneiss and Adakite properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Adakite belongs to Igneous Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Adakite is Porphyritic. Gneiss appears Foliated and Adakite appears Dull and Soft. The luster of Gneiss is dull while that of Adakite is grainy, pearly and vitreous. Gneiss is available in black, brown, pink, red, white colors whereas Adakite is available in black, brown, light to dark grey colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Adakite are commemorative tablets, pottery, used in aquariums.