1 Definition
1.1 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
Rhomb-porphyry is a porphyritic igneous rock with abundant wedge or lens shaped anorthoclase or feldspar phenocrysts
1.2 History
1.2.1 Origin
1.2.2 Discoverer
1.3 Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From Latin term that means purple
1.4 Class
Metamorphic Rocks
Igneous Rocks
1.4.1 Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
1.5 Family
1.5.1 Group
1.6 Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
2 Texture
2.1 Texture
Banded, Foliated, Platy
Aphanitic to Porphyritic
2.2 Color
Black, Brown, Pink, Red, White
Black, Brown, Colourless, Green, Grey, Pink, White
2.3 Maintenance
2.4 Durability
2.4.1 Water Resistant
2.4.2 Scratch Resistant
2.4.3 Stain Resistant
2.4.4 Wind Resistant
2.4.5 Acid Resistant
2.5 Appearance
3 Uses
3.1 Architecture
3.1.1 Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
3.1.2 Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
3.1.3 Other Architectural Uses
3.2 Industry
3.2.1 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, Cement Manufacture, for Road Aggregate, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
3.2.2 Medical Industry
Not Yet Used
Not Yet Used
3.3 Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
3.4 Other Uses
3.4.1 Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
An Oil and Gas Reservoir, As a Feed Additive for Livestock, Metallurgical Flux, Soil Conditioner, Source of Magnesia (MgO)
4 Types
4.1 Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Not Available
4.2 Features
Generally rough to touch, Is one of the oldest rock
Host Rock for Lead
4.3 Archaeological Significance
4.3.1 Monuments
4.3.2 Famous Monuments
Konark Sun Temple in India, Washington Monument, US
Data Not Available
4.3.3 Sculpture
4.3.4 Famous Sculptures
Not Applicable
Data Not Available
4.3.5 Pictographs
4.3.6 Petroglyphs
4.3.7 Figurines
4.4 Fossils
5 Formation
5.1 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.
Rhomb-porphyry is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
5.2 Composition
5.2.1 Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Alkali feldspar, Biotite, Plagioclase, Pyroxene
5.2.2 Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
CaO, Cl, MgO
5.3 Transformation
5.3.1 Metamorphism
5.3.2 Types of Metamorphism
Impact Metamorphism
Impact Metamorphism
5.3.3 Weathering
5.3.4 Types of Weathering
Biological Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
5.3.5 Erosion
5.3.6 Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Water Erosion
6 Properties
6.1 Physical Properties
6.1.1 Hardness
6.1.2 Grain Size
Medium to Coarse Grained
Fine Grained
6.1.3 Fracture
6.1.4 Streak
6.1.5 Porosity
Very Less Porous
Very Less Porous
6.1.6 Luster
6.1.7 Compressive Strength
125.00 N/mm2310.00 N/mm2
0.15
450
6.1.8 Cleavage
6.1.9 Toughness
6.1.10 Specific Gravity
6.1.11 Transparency
Translucent to Opaque
Translucent
6.1.12 Density
2.6-2.9 g/cm32.8-2.9 g/cm3
0
1400
6.2 Thermal Properties
6.2.1 Specific Heat Capacity
6.2.2 Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Pressure Resistant
7 Reserves
7.1 Deposits in Eastern Continents
7.1.1 Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Not Yet Found
7.1.2 Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Not Yet Found
7.1.3 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
7.1.4 Others
Not Yet Found
Not Yet Found
7.2 Deposits in Western Continents
7.2.1 North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
USA
7.2.2 South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Not Yet Found
7.3 Deposits in Oceania Continent
7.3.1 Australia
New South Wales, New Zealand, Queensland, Victoria
Not Yet Found