Gneiss and Siltstone
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
Siltstone can be defined as a fine-grained sedimentary rock which mainly consists of consolidated silt
History
Discoverer
Unknown
Unknown
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From English word silt and stone and from Proto-Indo-European root sal and stainaz
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Banded, Foliated, Platy
Clastic
Color
Black, Brown, Pink, Red, White
Brown, Red, Reddish Brown
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
No
Wind Resistant
Yes
Yes
Acid Resistant
No
Yes
Appearance
Foliated
Rough
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
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
Building houses or walls, 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, Sculpture, Small Figurines
Other Uses
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Raw material for the manufacture of mortar, Soil Conditioner
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
Available in Lots of Colors and Patterns, Easily splits into thin plates, Generally rough to touch, High silica content, Very fine grained rock
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
Not Applicable
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Not Used
Not Used
Petroglyphs
Not Used
Not Used
Figurines
Not Yet Used
Used
Fossils
Absent
Present
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.
Siltstone is a type of sedimentary rock which is formed from fine rock particles. As the particles of eroded rock travel along with water, the edges of the rock are worn-out by water into a rounded shape.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz, Sand, Silica, Silt
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, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Impact Metamorphism
Not Applicable
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
Chemical Erosion, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
7
6-7
Grain Size
Medium to Coarse Grained
Fine Grained
Fracture
Irregular
Conchoidal
Streak
White
White
Porosity
Very Less Porous
Highly Porous
Luster
Dull
Dull
Compressive Strength
125.00 N/mm2
17
Not Available
Cleavage
Poor
Not Available
Toughness
1.2
2.6
Specific Gravity
2.5-2.7
2.54-2.73
Transparency
Translucent to Opaque
Opaque
Density
2.6-2.9 g/cm3
2.6-2.7 g/cm3
Thermal Properties
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Water Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
China, India, Kazakhstan, Mongolia, Russia, Uzbekistan
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
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
Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom
Others
Not Yet Found
Greenland
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
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
New South Wales, New Zealand
All about Gneiss and Siltstone Properties
Know all about Gneiss and Siltstone properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Siltstone belongs to Sedimentary Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Siltstone is Clastic. Gneiss appears Foliated and Siltstone appears Rough. The luster of Gneiss and Siltstone is dull. Gneiss is available in black, brown, pink, red, white colors whereas Siltstone is available in brown, red, reddish brown colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Siltstone are raw material for the manufacture of mortar, soil conditioner.
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