Definition
Schist is a medium grade metamorphic rock with medium to large, flat, sheet like grains in a preferred orientation
Websterite is ultramafic and ultrabasic rock that consists of roughly equal proportions of orthopyroxene and clinopyroxene. It is a special type of pyroxenite.
History
Origin
-
Webster, North Carolina
Discoverer
Unknown
Unknown
Etymology
From French schiste, Greek skhistos i.e. split
From the town of Webster located in North Carolina
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
-
Plutonic
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Foliated, Platy
Clastic, Granular, Phaneritic, Porphyritic
Color
Black, Blue, Brown, Dark Brown, Green, Grey, Silver
Black to Grey, Bluish - Grey, Dark Greenish - Grey, Green, Light Greenish Grey
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Layered and Shiny
Layered, Banded, Veined and Shiny
Architecture
Interior Uses
Decorative Aggregates, Floor Tiles, Interior Decoration
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Interior Decoration
Exterior Uses
Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
-
Curbing
Industry
Construction Industry
As Dimension Stone, Building houses or walls, Cement Manufacture, for Road Aggregate, Roadstone
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
-
-
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
Used in aquariums, Writing Slates
Cemetery Markers, Commemorative Tablets, Creating Artwork, Laboratory bench tops, Jewelry, Sea Defence, Tombstones
Types
Mica Schists, Calc-Silicate Schists, Graphite Schists, Blueschists, Whiteschists, Greenschists, Hornblende Schist, Talc Schist, Chlorite Schist, Garnet Schist, Glaucophane schist.
Ultramafic rock
Features
Easily splits into thin plates, Smooth to touch
Generally rough to touch, Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
Schist formed by dynamic metamorphism at high temperatures and pressures that aligns the grains of mica, hornblende and other elongated minerals into thin layers.
Websterite can be formed as cumulates in ultramafic intrusions by accumulation of pyroxene crystals at the base of the lava chamber.
Composition
Mineral Content
Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc
Amphibole, Augite, Bronzite, Chromite, Diopside, Enstatite, Garnet, Hornblende, Hypersthene, Magnetite, Pyroxene
Compound Content
CaO, Carbon Dioxide, MgO
Aluminium Oxide, CaO, Chromium(III) Oxide, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Sulfur Trioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
-
Burial Metamorphism, Impact Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
3.5-47
1
7
👆🏻
Grain Size
Medium to Fine Coarse Grained
Coarse Grained
Fracture
Conchoidal
Uneven
Streak
White
White, Greenish White or Grey
Porosity
Highly Porous
Less Porous
Luster
Shiny
Dull to Vitreous to Submetallic
Compressive Strength
150.00 N/mm295.00 N/mm2
0.15
450
👆🏻
Cleavage
Slaty
-
Toughness
1.5
-
Specific Gravity
2.5-2.93.2-3.5
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm33.1-3.6 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.70 kJ/Kg K0.79 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Impact Resistant, Pressure Resistant, Water Resistant
Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam
India, Russia
Africa
Egypt, Ethiopia, Morocco, Nigeria, South Africa
South Africa
Europe
Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland
Germany, Greece, Italy, Scotland, Turkey
Others
-
Greenland
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
Canada, USA
South America
Brazil, Colombia, Guyana
Brazil, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland
New Zealand, Queensland