Slate and Comendite
Definition
Definition
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism
Comendite is a hard, peralkaline igneous rock, a type of light blue grey rhyolite
History
Origin
England
Italy
Discoverer
Unknown
Unknown
Etymology
From Old French esclate, from esclat (French éclat)
Comendite derives its name from the area of Le Commende on San Pietro Island in Italy
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Medium Grained Rock, Opaque Rock
Texture
Texture
Foliated
Porphyritic
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
Blue, Bluish - Grey
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
Yes
Wind Resistant
No
Yes
Acid Resistant
No
Yes
Appearance
Dull
Foliated
Uses
Architecture
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Countertops, 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, Landscaping, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts
Other Uses
Commercial Uses
Blackboards, Commemorative Tablets, Laboratory bench tops, Standard material for the bed of Billiard table, Standard material for the beds of Pool and Snooker table, Tombstones, Used in aquariums, Writing Slates
Cemetery Markers
Types
Types
Not Available
Rhyolite
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
Very fine grained rock, It is One of the Oldest, Strongest and Hardest Rock
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Data Not Available
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Not Yet Used
Fossils
Absent
Absent
Formation
Formation
Slate is a low grade metamorphic rock that is generally formed by metamorphosis of mudstone or shale, under relatively low pressure and temperature conditions.
Comendite is a type of Igneous rock which is formed due to cooling and solidification of lava or magma. It may form with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Composition
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
Albite, Amphibole, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Al, Fe, Potassium Oxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Cataclastic Metamorphism, Regional Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Coastal Erosion, Water Erosion
Properties
Physical Properties
Hardness
3-4
6-7
Grain Size
Very fine-grained
Medium Grained
Fracture
Splintery
Pervasive
Streak
Light to dark brown
Bluish Black
Porosity
Less Porous
Highly Porous
Luster
Dull
Dull
Compressive Strength
30.00 N/mm2
30
92.40 N/mm2
21
Cleavage
Slaty
Not Available
Toughness
1.2
2
Specific Gravity
2.65-2.8
2.38
Transparency
Opaque
Opaque
Density
2.6-2.8 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
0.76 kJ/Kg K
17
Not Available
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Turkey
China
Africa
Not Yet Found
East Africa
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
Italy
Others
Arctic
Not Yet Found
Deposits in Western Continents
North America
USA
Not Yet Found
South America
Brazil
Not Yet Found
Deposits in Oceania Continent
Australia
Not Yet Found
Queensland
All about Slate and Comendite Properties
Know all about Slate and Comendite properties here. All properties of rocks are important as they define the type of rock and its application. Slate belongs to Metamorphic Rocks while Comendite belongs to Igneous Rocks.Texture of Slate is Foliated whereas that of Comendite is Porphyritic. Slate appears Dull and Comendite appears Foliated. The luster of Slate and Comendite is dull. Slate is available in black, brown, buff, green, light to dark grey, purple, red, shades of blue colors whereas Comendite is available in blue, bluish - grey colors. The commercial uses of Slate are blackboards, commemorative tablets, laboratory bench tops, standard material for the bed of billiard table, standard material for the beds of pool and snooker table, tombstones, used in aquariums, writing slates and that of Comendite are cemetery markers.
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