Gneiss and Gossan
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
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
History
Origin
Unknown
Indonesia
Discoverer
Unknown
Cornish Gossen
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From Cornish gossen from gos, blood from Old Cornish guit
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Banded, Foliated, Platy
Rough, Sandy
Color
Black, Brown, Pink, Red, White
Brown, Brown- Black, Gold, Green, Rust
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
Dull and Banded
Uses
Architecture
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Countertops, Decorative Aggregates, 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
Curbing
Industry
Construction Industry
As Dimension Stone
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Cemetery Markers, Commemorative Tablets, Gemstone
Types
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Translocated gossan and Leakage gossan
Features
Generally rough to touch, Is one of the oldest rock
Clasts are smooth to touch, Easily splits into thin plates
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
Not Applicable
Sculpture
Not Yet Used
Not Yet Used
Famous Sculptures
Not Applicable
Not Applicable
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Not Yet Used
Not Yet 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.
Earth movements can cause rocks to be either deeply buried or squeezed and hence the rocks are heated and put under great pressure.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon
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, Fe, FeO, Silicon Dioxide, Sulphur
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Impact Metamorphism
Not Applicable
Weathering
Yes
No
Types of Weathering
Biological Weathering, Mechanical Weathering
Not Applicable
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Properties
Physical Properties
Hardness
7
4-5
Grain Size
Medium to Coarse Grained
Fine to Medium Grained
Fracture
Irregular
Conchoidal
Streak
White
White to Grey
Porosity
Very Less Porous
Highly Porous
Luster
Dull
Metallic
Compressive Strength
125.00 N/mm2
17
Not Available
Cleavage
Poor
Not Available
Toughness
1.2
Not Available
Specific Gravity
2.5-2.7
2.0
Transparency
Translucent to Opaque
Opaque
Density
2.6-2.9 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
Not Available
0.24 kJ/Kg K
24
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
China, India, Indonesia, Russia, Singapore, South Korea
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Cape Verde, Ethiopia, Ghana, 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
Albania, France, Germany, Great Britain, United Kingdom
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
Brazil, Colombia, Ecuador
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
New South Wales, South Australia, Western Australia
All about Gneiss and Gossan Properties
Know all about Gneiss and Gossan properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss and Gossan belong to Metamorphic Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Gossan is Rough, Sandy. Gneiss appears Foliated and Gossan appears Dull and Banded. The luster of Gneiss is dull while that of Gossan is metallic. Gneiss is available in black, brown, pink, red, white colors whereas Gossan is available in brown, brown- black, gold, green, rust colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Gossan are cemetery markers, commemorative tablets, gemstone.
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