Ignimbrite and Chert
Definition
Definition
Ignimbrite is a volcanic rock consisting mainly of pumice fragments, formed by the consolidation of material deposited by pyroclastic flows
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
History
Origin
New Zealand
Unknown
Discoverer
Patrick Marshall
Unknown
Etymology
From Latin ignis fire + imber, imbr- shower of rain, storm cloud + -ite
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
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
Texture
Aphanitic
Banded, Rough
Color
Beige, Black, Brown, Grey, Pink, White
Black, Brown, Green, Grey, Red, White
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
No
Yes
Wind Resistant
Yes
No
Acid Resistant
No
Yes
Appearance
Dull, Vesicular and Foilated
Glassy or Pearly
Uses
Architecture
Interior Uses
Decorative Aggregates, Floor Tiles, Homes, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Building houses or walls, Construction Aggregate
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Artifacts, Monuments
Other Uses
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Types
Not Available
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Always found as volcanic pipes over deep continental crust
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Used
Not Yet Used
Famous Sculptures
Data Not Available
Not Applicable
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Not Yet Used
Fossils
Absent
Present
Formation
Formation
Ignimbrites are formed from very poorly sorted mixture of volcanic ash or tuff and pumice lapilli, commonly with scattered lithic fragments.
Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.
Composition
Mineral Content
Apatite, Biotite, Calcite, Chlorite, Feldspar, Hematite, Hornblade, Ilmenite, Magnetite, Olivine, Pyroxene, Quartz
Quartz, Silicon
Compound Content
Ca, NaCl
Silicon Dioxide
Transformation
Metamorphism
Yes
No
Types of Metamorphism
Burial Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Not Applicable
Weathering
Yes
No
Types of Weathering
Biological Weathering, Chemical Weathering
Not Applicable
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion
Chemical Erosion
Properties
Physical Properties
Hardness
4-6
6.5-7
Grain Size
Fine Grained
Very fine-grained
Fracture
Uneven
Uneven, Splintery or Conchoidal
Streak
White
White
Porosity
Highly Porous
Highly Porous
Luster
Vitreous to Dull
Waxy and Dull
Compressive Strength
243.80 N/mm2
5
450.00 N/mm2
1
Cleavage
Not Available
Non-Existent
Toughness
Not Available
1.5
Specific Gravity
2.73
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
1-1.8 g/cm3
2.7 g/cm3
Thermal Properties
Specific Heat Capacity
0.20 kJ/Kg K
25
0.74 kJ/Kg K
19
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear 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, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Cameroon, Cape Verde, Chad, Djibouti, Eritrea, Ethiopia, Kenya, Libya, Madagascar, Nigeria, Rwanda, South Africa, Sudan, Tanzania, Uganda
Kenya, Morocco, South Africa, Tanzania
Europe
France, Georgia, Germany, Greece, Iceland, Italy, Netherlands, Poland, Portugal, Spain, United Kingdom
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Antarctica, Hawaii Islands
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, Costa Rica, Panama, USA
Canada, Mexico, USA
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador
Bolivia, Brazil
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New South Wales, Queensland, South Australia, Western Australia
All about Ignimbrite and Chert Properties
Know all about Ignimbrite and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Ignimbrite belongs to Igneous Rocks while Chert belongs to Sedimentary Rocks.Texture of Ignimbrite is Aphanitic whereas that of Chert is Banded, Rough. Ignimbrite appears Dull, Vesicular and Foilated and Chert appears Glassy or Pearly. The luster of Ignimbrite is vitreous to dull while that of Chert is waxy and dull. Ignimbrite is available in beige, black, brown, grey, pink, white colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Ignimbrite are cemetery markers, commemorative tablets, creating artwork and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.
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