Definition
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption
Websterite is ultramafic and ultrabasic rock that consists of roughly equal proportions of orthopyroxene and clinopyroxene. It is a special type of pyroxenite.
History
Origin
Italy
Webster, North Carolina
Discoverer
Unknown
Unknown
Etymology
From a Latin word tophous then in Italian tufo and finally tuff
From the town of Webster located in North Carolina
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Volcanic
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Clastic, Pyroclastic
Clastic, Granular, Phaneritic, Porphyritic
Color
Brown, Grey, Yellow
Black to Grey, Bluish - Grey, Dark Greenish - Grey, Green, Light Greenish Grey
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Dull, Vesicular and Foilated
Layered, Banded, Veined and Shiny
Architecture
Interior Uses
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Building houses or walls, Construction Aggregate
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts
Other Uses
Commercial Uses
Creating Artwork
Cemetery Markers, Commemorative Tablets, Creating Artwork, Laboratory bench tops, Jewelry, Sea Defence, Tombstones
Types
Welded tuff, Rhyolitic tuff, Basaltic tuff, Trachyte tuff, Andesitic tuff and Ignimbrite.
Ultramafic rock
Features
Always found as volcanic pipes over deep continental crust
Generally rough to touch, Is one of the oldest rock
Archaeological Significance
Monuments
-
-
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
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.
Websterite can be formed as cumulates in ultramafic intrusions by accumulation of pyroxene crystals at the base of the lava chamber.
Composition
Mineral Content
Calcite, Chlorite
Amphibole, Augite, Bronzite, Chromite, Diopside, Enstatite, Garnet, Hornblende, Hypersthene, Magnetite, Pyroxene
Compound Content
Hydrogen Sulfide, Sulfur Dioxide
Aluminium Oxide, CaO, Chromium(III) Oxide, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Sulfur Trioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Impact Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Water Erosion, Wind Erosion
Physical Properties
Hardness
4-67
1
7
👆🏻
Grain Size
Fine Grained
Coarse Grained
Fracture
Uneven
Uneven
Streak
White
White, Greenish White or Grey
Porosity
Highly Porous
Less Porous
Luster
Vitreous to Dull
Dull to Vitreous to Submetallic
Compressive Strength
243.80 N/mm295.00 N/mm2
0.15
450
👆🏻
Cleavage
-
-
Toughness
-
-
Specific Gravity
2.733.2-3.5
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
1-1.8 g/cm33.1-3.6 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.20 kJ/Kg K0.79 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Impact Resistant, Pressure Resistant, Wear 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
India, Russia
Africa
Cameroon, Cape Verde, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Uganda
South Africa
Europe
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
Germany, Greece, Italy, Scotland, Turkey
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, Colombia, Venezuela
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New Zealand, Queensland