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Slate and Variolite


Variolite and Slate


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   
Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance   

History
  
  

Origin
England   
France   

Discoverer
Unknown   
Unknown   

Etymology
From Old French esclate, from esclat (French éclat)   
From Latin varius, speckled, variegated   

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   
Opaque Rock   

Texture

Texture
Foliated   
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular   

Color
Black, Brown, Buff, Green, Light to Dark Grey, Purple, Red, Shades of Blue   
Black, Brown, Light to Dark Grey   

Maintenance
Less   
Less   

Durability
Durable   
Durable   

Water Resistant
Yes   
Yes   

Scratch Resistant
Yes   
Yes   

Stain Resistant
Yes   
No   

Wind Resistant
No   
No   

Acid Resistant
No   
Yes   

Appearance
Dull   
Dull and Soft   

Uses

Architecture
  
  

Interior Uses
Bathrooms, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Interior Decoration, Kitchens, Stair Treads   
Floor Tiles, Flooring, Homes, Hotels, Kitchens   

Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone   
Garden Decoration, Office Buildings   

Other Architectural Uses
Curbing   
Curbing   

Industry
  
  

Construction Industry
As Dimension Stone   
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone   

Medical Industry
Not Yet Used   
Not Yet Used   

Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines   
Artifacts, Monuments, Sculpture   

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, Creating Artwork   

Types

Types
Not Available   
Not Available   

Features
Easily splits into thin plates, Surfaces are often shiny, Very fine grained rock   
Has High structural resistance against erosion and climate, Very fine grained rock   

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   
Used   

Petroglyphs
Used   
Used   

Figurines
Used   
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.   
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.   

Composition
  
  

Mineral Content
Apatite, Biotite, Chlorite, Feldspar, Graphite, Hematite, Kaolinite, Magnetite, Pyrite, Tourmaline, Zircon   
Olivine, Plagioclase, Pyroxene   

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   
Yes   

Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism   
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism   

Weathering
Yes   
Yes   

Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering   
Biological Weathering, Chemical Weathering, Mechanical Weathering   

Erosion
Yes   
No   

Types of Erosion
Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion   
Not Applicable   

Properties

Physical Properties
  
  

Hardness
3-4   
6   

Grain Size
Very fine-grained   
Not Applicable   

Fracture
Splintery   
Conchoidal   

Streak
Light to dark brown   
White to Grey   

Porosity
Less Porous   
Less Porous   

Luster
Dull   
Not Available   

Compressive Strength
30.00 N/mm2   
30
37.50 N/mm2   
27

Cleavage
Slaty   
Not Available   

Toughness
1.2   
2.3   

Specific Gravity
2.65-2.8   
2.8-3   

Transparency
Opaque   
Opaque   

Density
2.6-2.8 g/cm3   
2.9-3.1 g/cm3   

Thermal Properties
  
  

Specific Heat Capacity
0.76 kJ/Kg K   
17
0.84 kJ/Kg K   
15

Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant   
Heat Resistant, Pressure Resistant, Wear Resistant   

Reserves

Deposits in Eastern Continents
  
  

Asia
China, India, Turkey   
India, Russia   

Africa
Not Yet Found   
South Africa   

Europe
Belgium, France, Germany, Italy, Norway, Portugal, Spain, United Kingdom   
Iceland   

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   
Not Yet Found   

Summary >>
<< Reserves

All about Slate and Variolite Properties

Know all about Slate and Variolite properties here. All properties of rocks are important as they define the type of rock and its application. Slate belongs to Metamorphic Rocks while Variolite belongs to Igneous Rocks.Texture of Slate is Foliated whereas that of Variolite is Glassy, Massive, Porphyritic, Scoriaceous, Vesicular. Slate appears Dull and Variolite appears Dull and Soft. The luster of Slate is dull while that of Variolite is not available. Slate and Variolite are available in black, brown, buff, green, light to dark grey, purple, red, shades of blue 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 Variolite are cemetery markers, creating artwork.

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