Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture
Discoverer
Unknown
Unknown
Etymology
From German Grauwacke, from grau grey + wacke
From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Clastic
Banded, Rough
Color
Beige, Black, Brown, Cream, Dark Brown, Green, Grey, Light Green, Light to Dark Grey, Pink, Red, White, Yellow
Black, Brown, Green, Grey, Red, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull
Glassy or Pearly
Interior Uses
Decorative Aggregates, Floor Tiles, Flooring, Homes, Interior Decoration
Decorative Aggregates, Homes
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing, Whetstones
Curbing
Construction Industry
Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Raw material for the manufacture of mortar
Arrowheads, Construction Aggregate, Cutting Tool, Spear Points
Antiquity Uses
Artifacts, Sculpture, Small Figurines
Artifacts, Monuments
Commercial Uses
As armour rock for sea walls, Petroleum reservoirs, Sea Defence, Tombstones
Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms
Types
Greywacke
Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter
Features
Available in Lots of Colors and Patterns, Generally rough to touch, Non-vesicular, Veined
Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate
Archaeological Significance
Formation
Graywacke rock is a type of sedimentary rock, which is also known as immature sandstone, which is indurated, dark grey and consisting of poorly sorted angular to sub-angular, sand-sized grains.
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.
Mineral Content
Augite, Biotite, Calcite, Chlorite, Clay, Clay Minerals, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz
Quartz, Silicon
Compound Content
Aluminium Oxide, NaCl, CaO, Chromium(III) Oxide, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Silicon Dioxide
Types of Metamorphism
-
-
Types of Weathering
Biological Weathering, Chemical Weathering
-
Types of Erosion
Coastal Erosion, Sea Erosion, Wind Erosion
Chemical Erosion
Grain Size
Angular and Fine
Very fine-grained
Fracture
Conchoidal
Uneven, Splintery or Conchoidal
Porosity
Highly Porous
Highly Porous
Luster
Dull
Waxy and Dull
Specific Gravity
2.2-2.8
2.5-2.8
Transparency
Opaque
Translucent to Opaque
Density
2.6-2.61 g/cm3
2.7 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Kazakhstan, Mongolia, Russia, Uzbekistan
China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam
Africa
Namibia, Nigeria, South Africa
Kenya, Morocco, South Africa, Tanzania
Europe
Austria, Denmark, Germany, Great Britain, Netherlands, Norway, Poland, Sweden, Switzerland, United Kingdom
Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom
Others
Greenland
Greenland, Mid-Atlantic Ridge
Deposits in Western Continents
North America
Canada, USA
Canada, Mexico, USA
South America
Brazil
Bolivia, Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand
New South Wales, Queensland, South Australia, Western Australia
All about Greywacke and Chert Properties
Know all about Greywacke and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Greywacke and Chert belong to Sedimentary Rocks.Texture of Greywacke is Clastic whereas that of Chert is Banded, Rough. Greywacke appears Dull and Chert appears Glassy or Pearly. The luster of Greywacke is dull while that of Chert is waxy and dull. Greywacke and Chert are available in beige, black, brown, cream, dark brown, green, grey, light green, light to dark grey, pink, red, white, yellow colors. The commercial uses of Greywacke are as armour rock for sea walls, petroleum reservoirs, sea defence, tombstones and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.