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
History
Origin
-
Discoverer
Unknown
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
Class
Metamorphic Rocks
Sub-Class
Durable Rock, Hard Rock
Family
Group
-
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Banded, Foliated, Platy
Color
Black, Brown, Pink, Red, White
Maintenance
More
Durability
Durable
Water Resistant
✔
✘
81% - Metamorphic Rocks Rocks have it !
Scratch Resistant
✔
✘
65% - Metamorphic Rocks Rocks have it !
Stain Resistant
✔
✘
42% - Metamorphic Rocks Rocks have it !
Wind Resistant
✔
✘
19% - Metamorphic Rocks Rocks have it !
Acid Resistant
✔
✘
15% - Metamorphic Rocks Rocks
Appearance
Foliated
Architecture
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Industry
Construction Industry
As Dimension Stone
Medical Industry
-
Antiquity Uses
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Features
Generally rough to touch, Is one of the oldest 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.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
✔
✘
50% - Metamorphic Rocks Rocks have it !
Types of Metamorphism
Impact Metamorphism
Weathering
✔
✘
65% - Metamorphic Rocks Rocks have it !
Types of Weathering
Biological Weathering, Mechanical Weathering
Erosion
✔
✘
77% - Metamorphic Rocks Rocks have it !
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Physical Properties
Hardness
7
1
7
👆🏻
Grain Size
Medium to Coarse Grained
Fracture
Irregular
Streak
White
Porosity
Very Less Porous
Luster
Dull
Compressive Strength
125.00 N/mm2
Rank: 25 (Overall)
0.15
450
👆🏻
Cleavage
-
Toughness
1.2
Specific Gravity
2.5-2.7
0
8.4
👆🏻
Transparency
Translucent to Opaque
Density
2.6-2.9 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.70 kJ/Kg K
Rank: 24 (Overall)
0.14
3.2
👆🏻
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Europe
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom
Others
-
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria