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
  
Amphibolite can be defined as a granular metamorphic rock which mainly consist of hornblende and plagioclase
  
History
  
  
Origin
England
  
Unknown
  
Discoverer
Unknown
  
Alexandre Brongniart
  
Etymology
From Old French esclate, from esclat (French éclat)
  
From Amphibole + -ite
  
Class
Metamorphic Rocks
  
Metamorphic 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
  
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
  
Texture
Foliated
  
Banded, Foliated, Massive
  
Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue
  
Black, Brown, Green, Grey
  
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
  
Foliated
  
Architecture
  
  
Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads
  
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Kitchens
  
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
As Dimension Stone
  
As Dimension Stone, Building houses or walls, Cobblestones, Construction Aggregate, for Road Aggregate, Landscaping, Production of Glass and Ceramics, Roadstone
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Sculpture, Small Figurines
  
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, Commemorative Tablets, Creating Artwork
  
Types
Not Available
  
Hornblendite
  
Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock
  
Clasts are smooth to touch, Matrix variable, Surfaces are often shiny
  
Archaeological Significance
  
  
Monuments
Used
  
Used
  
Famous Monuments
Data Not Available
  
Data Not Available
  
Sculpture
Used
  
Used
  
Famous Sculptures
Data Not Available
  
Data Not Available
  
Pictographs
Used
  
Not Used
  
Petroglyphs
Used
  
Not Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Absent
  
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.
  
Amphibolite is a coarse-grained metamorphic rock which forms by metamorphism of mafic igneous rocks like basalt and gabbro or from the metamorphism of clay-rich sedimentary rocks like marl or graywacke.
  
Composition
  
  
Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon
  
Amphibole, Andalusite, Biotite, Calcite, Epidote, Garnet, Hornblade, Kyanite, Magnetite, Olivine, Plagioclase, Pyroxene, Staurolite, Wollastonite
  
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
  
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
No
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
  
Not Applicable
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Glacier Erosion, Sea Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
3-4
  
6-7
  
Grain Size
Very fine-grained
  
Medium to Coarse Grained
  
Fracture
Splintery
  
Irregular to Conchoidal
  
Streak
Light to dark brown
  
White to Grey
  
Porosity
Less Porous
  
Less Porous
  
Luster
Dull
  
Vitreous to Dull
  
Compressive Strength
30.00 N/mm
2
  
30
Not Available
  
Cleavage
Slaty
  
Irregular
  
Toughness
1.2
  
2.3
  
Specific Gravity
2.65-2.8
  
2.5
  
Transparency
Opaque
  
Opaque
  
Density
2.6-2.8 g/cm3
  
2.85-3.07 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.76 kJ/Kg K
  
17
Not Available
  
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant, Pressure Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
China, India, Turkey
  
Russia, Turkey
  
Africa
Not Yet Found
  
Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Rwanda, Somalia, South Africa, Sudan, Tanzania, Uganda
  
Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom
  
Germany, Greece, Iceland, Norway, Poland
  
Others
Arctic
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
USA
  
Canada, USA
  
South America
Brazil
  
Brazil
  
Deposits in Oceania Continent
  
  
Australia
Not Yet Found
  
South Australia, Western Australia