Definition
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
Discoverer
Johann Gottlob Lehmann
Unknown
Etymology
From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,
From a Latin word tophous then in Italian tufo and finally tuff
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic, Splintery
Clastic, Pyroclastic
Color
Black, Brown, Buff, Green, Grey, Red, Yellow
Brown, Grey, Yellow
Durability
Durable
Durable
Appearance
Muddy
Dull, Vesicular and Foilated
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Building houses or walls, Construction Aggregate
Antiquity Uses
Artifacts, Sculpture
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Creating Artwork, Pottery
Creating Artwork
Types
Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale
Welded tuff, Rhyolitic tuff, Basaltic tuff, Trachyte tuff, Andesitic tuff and Ignimbrite.
Features
Easily splits into thin plates, Generally rough to touch, Very fine grained rock
Always found as volcanic pipes over deep continental crust
Archaeological Significance
Famous Monuments
Jantar Mantar in India
Easter Island in the Polynesian Triangle, Pacific Ocean
Formation
Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.
Tuff is formed when large masses of ash and sand which are mixed with hot gases are ejected by a volcano and avalanche rapidly down its slopes.
Mineral Content
Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides
Calcite, Chlorite
Compound Content
Ca, Fe, Mg, Silicon Dioxide, Sodium
Hydrogen Sulfide, Sulfur Dioxide
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Very fine-grained
Fine Grained
Porosity
Highly Porous
Highly Porous
Luster
Dull
Vitreous to Dull
Specific Gravity
2.2-2.8
2.73
Transparency
Opaque
Opaque
Density
2.4-2.8 g/cm3
1-1.8 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Bangladesh, China, India, Russia
Afghanistan, Armenia, Azerbaijan, Burma, Cambodia, China, India, Indonesia, Iran, Japan, Malaysia, Mongolia, Nepal, North Korea, Pakistan, Saudi Arabia, Syria, Taiwan, Thailand, Turkey, Vietnam, Yemen
Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Cameroon, Cape Verde, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Uganda
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
Others
-
Antarctica, Hawaii Islands
Deposits in Western Continents
North America
USA
Canada, Costa Rica, Panama, USA
South America
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia
Central Australia, Western Australia