Gneiss

Syenite

Gneiss and Syenite

Gneiss

Syenite

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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

Syenite is a coarse-grained igneous rock which is composed mainly of alkali feldspar and various ferromagnesian minerals

History

Origin

Discoverer

Unknown

Etymology

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

From French syénite, from Latin Syenites (lapis ) (stone) of Syene

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Plutonic

Other Categories

Coarse Grained Rock, Medium Grained Rock, Opaque Rock

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

Texture

Banded, Foliated, Platy

Earthy

Color

Black, Brown, Pink, Red, White

Brown, Buff, Cream, Green, Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Foliated

Banded and Foilated

Uses

Architecture

Interior Uses

Countertops, Decorative Aggregates, Flooring, Interior Decoration

Flooring, Homes, Hotels, Interior Decoration

Exterior Uses

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

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

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone

As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and Dolomite Refractories

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Cemetery Markers, Jewelry, Tombstones, Used in aquariums

Cemetery Markers, Creating Artwork

Types

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

Shonkinite

Features

Generally rough to touch, Is one of the oldest rock

Available in Lots of Colors and Patterns, Is one of the oldest rock, Matrix variable

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.

Syenites are formed due to alkaline igneous activities and are generally formed in thick continental crustal areas or in Cordilleran subduction zones.

Composition

Mineral Content

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

Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz

Compound Content

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

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

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

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion

Properties

Physical Properties

Hardness

75.5-6

1 7

👆🏻

Grain Size

Medium to Coarse Grained

Medium to Fine Coarse Grained

Fracture

Irregular

Streak

White

Porosity

Very Less Porous

Less Porous

Luster

Dull

Subvitreous to Dull

Compressive Strength

125.00 N/mm²150.00 N/mm²

0.15 450

👆🏻

Cleavage

Perfect

Toughness

1.2

Specific Gravity

2.5-2.72.6-2.7

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.6-2.9 g/cm³2.6-2.8 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, Impact Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

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

China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam

Africa

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

Angola, Egypt, Madagascar, Namibia, Nigeria, 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

Bulgaria, England, Germany, Norway, Romania, Switzerland

Others

Deposits in Western Continents

North America

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

USA

South America

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

Brazil, Chile

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland, Victoria

New Zealand, Queensland, South Australia, Western Australia

All about Gneiss and Syenite Properties

Know all about Gneiss and Syenite properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Syenite belongs to Igneous Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Syenite is Earthy. Gneiss appears Foliated and Syenite appears Banded and Foilated. The luster of Gneiss is dull while that of Syenite is subvitreous to dull. Gneiss is available in black, brown, pink, red, white colors whereas Syenite is available in brown, buff, cream, green, grey, pink, white colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Syenite are cemetery markers, creating artwork.