Definition
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
  
Siltstone can be defined as a fine-grained sedimentary rock which mainly consists of consolidated silt
  
History
  
  
Origin
Italy
  
Unknown
  
Discoverer
Unknown
  
Unknown
  
Etymology
From a Latin word tophous then in Italian tufo and finally tuff
  
From English word silt and stone and from Proto-Indo-European root sal and stainaz
  
Class
Igneous Rocks
  
Sedimentary Rocks
  
Sub-Class
Durable Rock, Medium Hardness Rock
  
Durable Rock, Hard Rock
  
Family
  
  
Group
Volcanic
  
Not Applicable
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Fine Grained Rock, Opaque Rock
  
Texture
Clastic, Pyroclastic
  
Clastic
  
Color
Brown, Grey, Yellow
  
Brown, Red, Reddish Brown
  
Maintenance
More
  
Less
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
No
  
No
  
Wind Resistant
No
  
Yes
  
Acid Resistant
No
  
Yes
  
Appearance
Dull, Vesicular and Foilated
  
Rough
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
  
Decorative Aggregates, Interior Decoration
  
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
  
As Building Stone, As Facing Stone, Garden Decoration
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
Building houses or walls, Construction Aggregate
  
Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
  
Artifacts, Sculpture, Small Figurines
  
Other Uses
  
  
Commercial Uses
Creating Artwork
  
Raw material for the manufacture of mortar, Soil Conditioner
  
Types
Welded tuff, Rhyolitic tuff, Basaltic tuff, Trachyte tuff, Andesitic tuff and Ignimbrite.
  
Not Available
  
Features
Always found as volcanic pipes over deep continental crust
  
Available in Lots of Colors and Patterns, Easily splits into thin plates, Generally rough to touch, High silica content, Very fine grained rock
  
Archaeological Significance
  
  
Monuments
Used
  
Not Yet Used
  
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean
  
Not Applicable
  
Sculpture
Used
  
Used
  
Famous Sculptures
Data Not Available
  
Data Not Available
  
Pictographs
Used
  
Not Used
  
Petroglyphs
Used
  
Not Used
  
Figurines
Used
  
Used
  
Fossils
Absent
  
Present
  
Formation
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.
  
Siltstone is a type of sedimentary rock which is formed from fine rock particles. As the particles of eroded rock travel along with water, the edges of the rock are worn-out by water into a rounded shape.
  
Composition
  
  
Mineral Content
Calcite, Chlorite
  
Calcite, Clay, Clay Minerals, Feldspar, Micas, Quartz, Sand, Silica, Silt
  
Compound Content
Hydrogen Sulfide, Sulfur Dioxide
  
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide
  
Transformation
  
  
Metamorphism
Yes
  
No
  
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Not Applicable
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Chemical Erosion, Coastal Erosion, Glacier Erosion
  
Physical Properties
  
  
Hardness
4-6
  
6-7
  
Grain Size
Fine Grained
  
Fine Grained
  
Fracture
Uneven
  
Conchoidal
  
Streak
White
  
White
  
Porosity
Highly Porous
  
Highly Porous
  
Luster
Vitreous to Dull
  
Dull
  
Compressive Strength
243.80 N/mm
2
  
5
Not Available
  
Cleavage
Not Available
  
Not Available
  
Toughness
Not Available
  
2.6
  
Specific Gravity
2.73
  
2.54-2.73
  
Transparency
Opaque
  
Opaque
  
Density
1-1.8 g/cm3
  
2.6-2.7 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.20 kJ/Kg K
  
25
Not Available
  
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant, Impact Resistant, Pressure Resistant, Water Resistant
  
Deposits in Eastern Continents
  
  
Asia
Afghanistan, Armenia, Azerbaijan, Burma, Cambodia, China, India, Indonesia, Iran, Japan, Malaysia, Mongolia, Nepal, North Korea, Pakistan, Saudi Arabia, Syria, Taiwan, Thailand, Turkey, Vietnam, Yemen
  
China, India, Kazakhstan, Mongolia, Russia, Uzbekistan
  
Africa
Cameroon, Cape Verde, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Uganda
  
Namibia, Nigeria, South Africa
  
Europe
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
  
Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom
  
Others
Antarctica, Hawaii Islands
  
Greenland
  
Deposits in Western Continents
  
  
North America
Canada, Costa Rica, Panama, USA
  
Canada, USA
  
South America
Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay
  
Brazil
  
Deposits in Oceania Continent
  
  
Australia
Central Australia, Western Australia
  
New South Wales, New Zealand