Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Nephelinite is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite).
Discoverer
Unknown
Unknown
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
from French néphéline, from Greek nephelē
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Banded, Rough
Aphanitic
Color
Black, Brown, Green, Grey, Red, White
Black, Brown, Green, Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Glassy or Pearly
Skeletal
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Creating Artwork, Soil Conditioner, Source of Magnesia (MgO)
Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Peralkaline Nephelinite
Features
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Host Rock for Lead
Archaeological Significance
Formation
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.
Nephelinite 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.
Mineral Content
Quartz, Silicon
Clinopyroxene, Nepheline, Plagioclase
Compound Content
Silicon Dioxide
Ca, CaO, Carbon, Cl, MgO
Types of Metamorphism
-
Contact Metamorphism
Types of Weathering
-
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion
Chemical Erosion, Water Erosion, Wind Erosion
Grain Size
Very fine-grained
Fine Grained
Fracture
Uneven, Splintery or Conchoidal
Flat
Porosity
Highly Porous
Less Porous
Luster
Waxy and Dull
Vitreous to Metallic
Specific Gravity
2.5-2.8
2.4-2.9
Transparency
Translucent to Opaque
Opaque
Density
2.7 g/cm3
2.5-3 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Japan
Africa
Kenya, Morocco, South Africa, Tanzania
Rwanda, Tanzania
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
-
Others
Greenland, Mid-Atlantic Ridge
Hawaii Islands
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Bolivia, Brazil
Colombia
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
-
All about Chert and Nephelinite Properties
Know all about Chert and Nephelinite properties here. All properties of rocks are important as they define the type of rock and its application. Chert belongs to Sedimentary Rocks while Nephelinite belongs to Igneous Rocks.Texture of Chert is Banded, Rough whereas that of Nephelinite is Aphanitic. Chert appears Glassy or Pearly and Nephelinite appears Skeletal. The luster of Chert is waxy and dull while that of Nephelinite is vitreous to metallic. Chert and Nephelinite are available in black, brown, green, grey, red, white colors. The commercial uses of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms and that of Nephelinite are creating artwork, soil conditioner, source of magnesia (mgo).