Gneiss and Dunite
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
Dunite is a green to brownish coarse-grained igneous rock mainly consisting of olivine
History
Origin
Unknown
New Zealand
Discoverer
Unknown
Ferdinand von Hochstetter
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From the name of Dun Mountain, New Zealand, + -ite1
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Not Applicable
Plutonic
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Texture
Banded, Foliated, Platy
Phaneritic
Color
Black, Brown, Pink, Red, White
Dark Greenish - Grey
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
Yes
Wind Resistant
Yes
No
Acid Resistant
No
No
Appearance
Foliated
Rough and Shiny
Uses
Architecture
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Other Uses
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Creating Artwork, Gemstone, Jewelry, Source of Chromite, Platinum, Nickel and Garnet, Source of Diamonds
Types
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Not Available
Features
Generally rough to touch, Is one of the oldest rock
Constitutes upper part of the Earth's mantle, Generally rough to touch, Host rock for Diamond, Is one of the oldest rock
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Not Yet Used
Used
Fossils
Absent
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.
Dunite is a plutonic ultramafic igneous rock consisting almost m olivine. It can be formed in two ways.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Amphibole, Chromite, Garnet, Magnesium, Olivine, Phlogopite, Plagioclase, Pyroxene
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, CaO, Fe, Potassium, Silicon Dioxide, Sodium, Titanium Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Impact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Coastal Erosion, Glacier Erosion, Water Erosion
Properties
Physical Properties
Hardness
7
3.5-4
Grain Size
Medium to Coarse Grained
Coarse Grained
Fracture
Irregular
Irregular
Streak
White
White
Porosity
Very Less Porous
Less Porous
Luster
Dull
Shiny
Compressive Strength
125.00 N/mm2
17
107.55 N/mm2
19
Cleavage
Poor
Imperfect
Toughness
1.2
2.1
Specific Gravity
2.5-2.7
3-3.01
Transparency
Translucent to Opaque
Translucent to Opaque
Density
2.6-2.9 g/cm3
2.84-2.85 g/cm3
Thermal Properties
Specific Heat Capacity
Not Available
1.25 kJ/Kg K
6
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
China, India, Indonesia, Kazakhstan, Russia, South Korea, Thailand, Turkey
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Morocco, 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
Finland, France, Georgia, Germany, Great Britain, Italy, Kazakhstan, Netherlands, Norway, Spain, Switzerland, Venezuela
Others
Not Yet Found
Not Yet Found
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
Argentina, Brazil, Colombia, Ecuador, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
New Zealand, Western Australia
All about Gneiss and Dunite Properties
Know all about Gneiss and Dunite properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Dunite belongs to Igneous Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Dunite is Phaneritic. Gneiss appears Foliated and Dunite appears Rough and Shiny. The luster of Gneiss is dull while that of Dunite is shiny. Gneiss is available in black, brown, pink, red, white colors whereas Dunite is available in dark greenish - grey colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Dunite are creating artwork, gemstone, jewelry, source of chromite, platinum, nickel and garnet, source of diamonds.
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