Phyllite and Gneiss
Definition
Definition
Phyllite is a fine-grained metamorphic rock with a well-developed laminar structure, and is intermediate between slate and schist rocks
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
Discoverer
Unknown
Unknown
Etymology
From Greek phullon leaf + -ite1
From the Middle High German verb gneist (to spark; so called because the rock glitters)
Class
Metamorphic Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Phyllitic Sheen, Slaty
Banded, Foliated, Platy
Color
Black to Grey, Light Greenish Grey
Black, Brown, Pink, Red, White
Maintenance
More
More
Durability
Durable
Durable
Water Resistant
No
Yes
Scratch Resistant
No
Yes
Stain Resistant
No
Yes
Wind Resistant
No
Yes
Acid Resistant
No
No
Appearance
Crinkled or Wavy
Foliated
Uses
Architecture
Interior Uses
Decorative Aggregates, Floor Tiles, Homes, Interior Decoration
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Raw material for the manufacture of mortar, Roadstone
As Dimension Stone
Medical Industry
Not Available
Not Available
Antiquity Uses
Artifacts, Sculpture
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork, Writing Slates
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Types
Types
Not Available
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Features
Easily splits into thin plates, Is one of the oldest rock, Surfaces are often shiny
Generally rough to touch, Is one of the oldest rock
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Konark Sun Temple in India, Washington Monument, US
Sculpture
Used
Not Yet Used
Famous Sculptures
Not Available
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Not Yet Used
Fossils
Absent
Absent
Formation
Formation
Phyllite is a metamorphic rock which is formed by regional metamorphism of argillaceous sediments since their cleavage arose due to deviatoric stress.
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
Albite, Alusite, Amphibole, Apatite, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc, Zircon
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Compound Content
CaO, Carbon Dioxide, MgO
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
No
Yes
Types of Metamorphism
Not Applicable
Impact Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Properties
Physical Properties
Hardness
1-2
7
Grain Size
Medium to Fine Coarse Grained
Medium to Coarse Grained
Fracture
Conchoidal
Irregular
Streak
White
White
Porosity
Highly Porous
Very Less Porous
Luster
Phyllitic
Dull
Compressive Strength
Not Available
125.00 N/mm2
17
Cleavage
Crenulation and Pervasive
Not Available
Toughness
1.2
1.2
Specific Gravity
2.72-2.73
2.5-2.7
Transparency
Opaque
Translucent to Opaque
Density
2.18-3.3 g/cm3
2.6-2.9 g/cm3
Thermal Properties
Resistance
Heat Resistant, Pressure Resistant, Water Resistant
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Africa
Egypt, Ethiopia, Morocco, Nigeria, South Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Europe
Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom
Others
Not Available
Not Available
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
Canada, Costa Rica, Cuba, Mexico, Panama, USA
South America
Brazil, Colombia, Guyana
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland
New South Wales, New Zealand, Queensland, Victoria
All about Phyllite and Gneiss Properties
Know all about Phyllite and Gneiss properties here. All properties of rocks are important as they define the type of rock and its application. Phyllite and Gneiss belong to Metamorphic Rocks.Texture of Phyllite is Phyllitic Sheen, Slaty whereas that of Gneiss is Banded, Foliated, Platy. Phyllite appears Crinkled or Wavy and Gneiss appears Foliated. The luster of Phyllite is phyllitic while that of Gneiss is dull. Phyllite is available in black to grey, light greenish grey colors whereas Gneiss is available in black, brown, pink, red, white colors. The commercial uses of Phyllite are cemetery markers, commemorative tablets, creating artwork, writing slates and that of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums.
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