Slate and Chert
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
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
History
Origin
England
Unknown
Discoverer
Unknown
Unknown
Etymology
From Old French esclate, from esclat (French éclat)
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Not Applicable
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Foliated
Banded, Rough
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
Black, Brown, Green, Grey, Red, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
Yes
Wind Resistant
No
No
Acid Resistant
No
Yes
Appearance
Dull
Glassy or Pearly
Uses
Architecture
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
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
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Types
Not Available
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Data Not Available
Data Not Available
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
Present
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.
Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.
Composition
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
Quartz, Silicon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Silicon Dioxide
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Not Applicable
Weathering
Yes
No
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Not Applicable
Erosion
Yes
Yes
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Chemical Erosion
Properties
Physical Properties
Hardness
3-4
6.5-7
Grain Size
Very fine-grained
Very fine-grained
Fracture
Splintery
Uneven, Splintery or Conchoidal
Streak
Light to dark brown
White
Porosity
Less Porous
Highly Porous
Luster
Dull
Waxy and Dull
Compressive Strength
30.00 N/mm2
30
450.00 N/mm2
1
Cleavage
Slaty
Non-Existent
Toughness
1.2
1.5
Specific Gravity
2.65-2.8
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
2.6-2.8 g/cm3
2.7 g/cm3
Thermal Properties
Specific Heat Capacity
0.76 kJ/Kg K
17
0.74 kJ/Kg K
19
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Turkey
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Not Yet Found
Kenya, Morocco, South Africa, Tanzania
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Arctic
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
USA
Canada, Mexico, USA
South America
Brazil
Bolivia, Brazil
Deposits in Oceania Continent
Australia
Not Yet Found
New South Wales, Queensland, South Australia, Western Australia
All about Slate and Chert Properties
Know all about Slate and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Slate belongs to Metamorphic Rocks while Chert belongs to Sedimentary Rocks.Texture of Slate is Foliated whereas that of Chert is Banded, Rough. Slate appears Dull and Chert appears Glassy or Pearly. The luster of Slate is dull while that of Chert is waxy and dull. Slate is available in black, brown, buff, green, light to dark grey, purple, red, shades of blue colors whereas Chert is available in black, brown, green, grey, red, white 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 Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.
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