Definition
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Shonkinite is a rare, dark-coloured and intrusive igneous rock which contains augite and orthoclase feldspar as its primary constituents
History
Origin
-
USA
Discoverer
Unknown
Unknown
Etymology
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
From the name of Shonkin Sag ranges in the Highwood Mountains of north-central Montana, US
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
-
-
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Banded, Rough
Earthy
Color
Black, Brown, Green, Grey, Red, White
Brown, Buff, Cream, Green, Grey, Pink, White
Maintenance
Less
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Glassy or Pearly
Banded and Foilated
Architecture
Interior Uses
Decorative Aggregates, Homes
Decorative Aggregates, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
Medical Industry
-
-
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Cemetery Markers, Creating Artwork
Types
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Igneous rock
Features
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Available in Lots of Colors and Patterns, Is one of the oldest rock, Matrix variable
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Present
Absent
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.
Shonkinites are formed due to alkaline igneous activities and are generally formed in thick continental crustal areas or in Cordilleran subduction zones.
Composition
Mineral Content
Quartz, Silicon
Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz
Compound Content
Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
✔
✘
✔
✘
Types of Weathering
-
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion, Water Erosion
Physical Properties
Hardness
6.5-75.5-6
1
7
👆🏻
Grain Size
Very fine-grained
Medium to Fine Coarse Grained
Fracture
Uneven, Splintery or Conchoidal
-
Streak
White
White
Porosity
Highly Porous
Less Porous
Luster
Waxy and Dull
Subvitreous to Dull
Compressive Strength
450.00 N/mm2150.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Perfect
Toughness
1.5
-
Specific Gravity
2.5-2.82.6-2.7
0
8.4
👆🏻
Transparency
Translucent to Opaque
Opaque
Density
2.7 g/cm32.6-2.8 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.74 kJ/Kg K0.92 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Africa
Kenya, Morocco, South Africa, Tanzania
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Bulgaria, England, Germany, Norway, Romania, Switzerland
Others
Greenland, Mid-Atlantic Ridge
-
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Bolivia, Brazil
Brazil, Chile
Deposits in Oceania Continent
Australia
New South Wales, Queensland, South Australia, Western Australia
New Zealand, Queensland, South Australia, Western Australia