Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
  
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
  
History
  
  
Origin
Unknown
  
England
  
Discoverer
Unknown
  
Unknown
  
Etymology
From German Grauwacke, from grau grey + wacke
  
From Old French esclate, from esclat (French éclat)
  
Class
Sedimentary Rocks
  
Metamorphic Rocks
  
Sub-Class
Durable Rock, Hard Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Not Applicable
  
Not Applicable
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Clastic
  
Foliated
  
Color
Beige, Black, Brown, Colourless, Cream, Dark Brown, Green, Grey, Light Green, Light to Dark Grey, Pink, Red, White, Yellow
  
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
  
Maintenance
Less
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
Yes
  
Yes
  
Wind Resistant
Yes
  
No
  
Acid Resistant
No
  
No
  
Appearance
Dull
  
Dull
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Floor Tiles, Flooring, Homes, Interior Decoration
  
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
  
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Curbing, Whetstones
  
Curbing
  
Industry
  
  
Construction Industry
Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Raw material for the manufacture of mortar
  
As Dimension Stone
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Sculpture, Small Figurines
  
Artifacts, Monuments, Sculpture, Small Figurines
  
Other Uses
  
  
Commercial Uses
As armour rock for sea walls, Petroleum reservoirs, Sea Defence, Tombstones
  
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
  
Types
Not Available
  
Not Available
  
Features
Available in Lots of Colors and Patterns, Generally rough to touch, Non-vesicular, Veined
  
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
  
Archaeological Significance
  
  
Monuments
Not Yet Used
  
Used
  
Famous Monuments
Not Applicable
  
Data Not Available
  
Sculpture
Used
  
Used
  
Famous Sculptures
Data Not Available
  
Data Not Available
  
Pictographs
Not Used
  
Used
  
Petroglyphs
Not Used
  
Used
  
Figurines
Used
  
Used
  
Fossils
Present
  
Absent
  
Formation
Graywacke rock is a type of sedimentary rock, which is also known as immature sandstone, which is indurated, dark grey and consisting of poorly sorted angular to sub-angular, sand-sized grains.
  
Slate is a low grade metamorphic rock that is generally formed by metamorphosis of mudstone or shale, under relatively low pressure and temperature conditions.
  
Composition
  
  
Mineral Content
Augite, Biotite, Calcite, Chlorite, Clay, Clay Minerals, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz
  
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
  
Compound Content
Aluminium Oxide, NaCl, CaO, Chromium(III) Oxide, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
  
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Transformation
  
  
Metamorphism
No
  
Yes
  
Types of Metamorphism
Not Applicable
  
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Coastal Erosion, Sea Erosion, Wind Erosion
  
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
6-7
  
3-4
  
Grain Size
Angular and Fine
  
Very fine-grained
  
Fracture
Conchoidal
  
Splintery
  
Streak
White
  
Light to dark brown
  
Porosity
Highly Porous
  
Less Porous
  
Luster
Dull
  
Dull
  
Compressive Strength
Not Available
  
30.00 N/mm
2
  
30
Cleavage
Perfect
  
Slaty
  
Toughness
2.6
  
1.2
  
Specific Gravity
2.2-2.8
  
2.65-2.8
  
Transparency
Opaque
  
Opaque
  
Density
2.6-2.61 g/cm3
  
2.6-2.8 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
0.76 kJ/Kg K
  
17
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
China, India, Kazakhstan, Mongolia, Russia, Uzbekistan
  
China, India, Turkey
  
Africa
Namibia, Nigeria, South Africa
  
Not Yet Found
  
Europe
Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom
  
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
  
Others
Greenland
  
Arctic
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
USA
  
South America
Brazil
  
Brazil
  
Deposits in Oceania Continent
  
  
Australia
New South Wales, New Zealand
  
Not Yet Found
  
All about Greywacke and Slate Properties
Know all about Greywacke and Slate properties here. All properties of rocks are important as they define the type of rock and its application. Greywacke belongs to Sedimentary Rocks while Slate belongs to Metamorphic Rocks.Texture of Greywacke is Clastic whereas that of Slate is Foliated. Greywacke appears Dull and Slate appears Dull. The luster of Greywacke and Slate is dull. Greywacke is available in beige, black, brown, colourless, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow colors whereas Slate is available in black, brown, buff, green, light to dark grey, purple, red, shades of blue colors. The commercial uses of Greywacke are as armour rock for sea walls, petroleum reservoirs, sea defence, tombstones and that 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.