Tuff and Rhyodacite
Definition
Definition
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
Rhyodacite is an extrusive volcanic rock intermediate in composition between dacite and rhyolite
History
Origin
Italy
USA
Discoverer
Unknown
Unknown
Etymology
From a Latin word tophous then in Italian tufo and finally tuff
Rhyo lite + dacite : a rock intermediate between rhyolite and dacite that is the extrusive equivalent of granodiorite
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Clastic, Pyroclastic
Earthy
Color
Brown, Grey, Yellow
Black to Grey, Dark Greenish - Grey
Maintenance
More
More
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
No
No
Wind Resistant
No
No
Acid Resistant
No
No
Appearance
Dull, Vesicular and Foilated
Skeletal
Uses
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, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Building houses or walls, Construction Aggregate
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts
Other Uses
Commercial Uses
Creating Artwork
Cemetery Markers, Creating Artwork
Types
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
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean
Not Applicable
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Used
Used
Petroglyphs
Used
Used
Figurines
Used
Not Yet Used
Fossils
Absent
Absent
Formation
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.
Rhyodacite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Composition
Mineral Content
Calcite, Chlorite
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Hydrogen Sulfide, Sulfur Dioxide
Ca, Fe, Potassium Oxide, NA, Potassium, Silicon Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact 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
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
4-6
5.5-6
Grain Size
Fine Grained
Fine Grained
Fracture
Uneven
Conchoidal
Streak
White
Black
Porosity
Highly Porous
Less Porous
Luster
Vitreous to Dull
Greasy to Dull
Compressive Strength
243.80 N/mm2
5
200.50 N/mm2
9
Cleavage
Not Available
Not Available
Toughness
Not Available
2.1
Specific Gravity
2.73
2.34-2.40
Transparency
Opaque
Opaque
Density
1-1.8 g/cm3
Not Available
Thermal Properties
Specific Heat Capacity
0.20 kJ/Kg K
25
1.12 kJ/Kg K
7
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant
Reserves
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, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Africa
Cameroon, Cape Verde, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Uganda
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
Austria, Belgium, Finland, France, Germany, Italy, Norway, Sardinia, Spain, Switzerland
Others
Antarctica, Hawaii Islands
Not Yet Found
Deposits in Western Continents
North America
Canada, Costa Rica, Panama, USA
Canada, USA
South America
Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay
Not Yet Found
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
Not Yet Found
All about Tuff and Rhyodacite Properties
Know all about Tuff and Rhyodacite properties here. All properties of rocks are important as they define the type of rock and its application. Tuff and Rhyodacite belong to Igneous Rocks.Texture of Tuff is Clastic, Pyroclastic whereas that of Rhyodacite is Earthy. Tuff appears Dull, Vesicular and Foilated and Rhyodacite appears Skeletal. The luster of Tuff is vitreous to dull while that of Rhyodacite is greasy to dull. Tuff is available in brown, grey, yellow colors whereas Rhyodacite is available in black to grey, dark greenish - grey colors. The commercial uses of Tuff are creating artwork and that of Rhyodacite are cemetery markers, creating artwork.
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