The Gay Head cliffs in Martha's Vineyard are made almost entirely of clay. Martha's Vineyard (adjoining the smaller Chappaquiddick Island) is an Island off the US east coast to the south of Cape Cod, both

Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Water content or moisture content is the quantity of Water contained in a material such as Soil (called soil moisture) rock, Clay deposits are mostly composed of clay minerals (phyllosilicate minerals), minerals which impart plasticity and harden when fired and/or dried, and variable amounts of water trapped in the mineral structure by polar attraction. Clay minerals are hydrous Aluminium phyllosilicates, sometimes with variable amounts of Iron, Magnesium, Alkali metals Alkaline The silicate minerals make up the largest and most important class of rock-forming Minerals They are classified based on the structure of their silicate Ion group "Polar molecule" and "Non-polar" redirect here Organic materials which do not impart plasticity may also be a part of clay deposits. Organic matter (or organic material) is Matter that has come from a once-living Organism; is capable of ^[1]

Clay minerals are typically formed over long periods of time by the gradual chemical weathering of rocks (usually silicate-bearing) by low concentrations of carbonic acid and other diluted solvents. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3 A solvent is a liquid or gas that dissolves a solid liquid or gaseous Solute, resulting in a Solution. These solvents (usually acidic) migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process, some clay minerals are formed by hydrothermal activity. Hydrothermal circulation in its most general sense is the circulation of hot water 'hydros' in the Greek meaning water and 'thermos' meaning heat Clay deposits may be formed in place as residual deposits, but thick deposits usually are formed as the result of a secondary sedimentary deposition process after they have been eroded and transported from their original location of formation. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Clay deposits are typically associated with very low energy depositional environments such as large lake and marine deposits.

Definition

Clays are distinguished from other fine-grained soils by various differences in composition. Silts, which are fine-grained soils which do not include clay minerals, tend to have larger particle sizes than clays, but there is some overlap in both particle size and other physical properties, and there are many naturally occurring deposits which include both silts and clays. Silt is Soil or rock derived Granular material of a Grain size between sand and clay The distinction between silt and clay varies by discipline. Silt is Soil or rock derived Granular material of a Grain size between sand and clay Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4-5 μm, and colloid chemists use 1 μm. A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system Soil science is the study of Soil as a Natural resource on the surface of the Earth including soil formation, classification and mapping A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre Sedimentology encompasses the study of modern Sediments such as sand, mud (silt and clay and understanding the processes that deposit them A chemist is a Scientist trained in the Science of Chemistry. ^[1] Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg Limits. Geotechnical engineering is the branch of Civil engineering concerned with the engineering behavior of earth materials The Atterberg limits are a basic measure of the nature of a fine-grained Soil. ISO 14688 grades clay particles as being smaller than 0. 063 mm, and silts larger.

Quaternary clay in Estonia. Overview The term Quaternary ("fourth" was proposed by Giovanni Arduino in 1759 for alluvial deposits in the Po river valley in northern Estonia, officially the Republic of Estonia ( Eesti or Eesti Vabariik) is a Country in Northern Europe in the Baltic region

Primary clays, also known as kaolins are located at the site of formation. Secondary clay deposits have been moved by erosion and water from its primary location^[2]. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind

Grouping

Depending upon academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite, illite, and chlorite. Kaolinite is a Clay mineral with the chemical composition Al 2 Si 2 O 5( OH)4 Montmorillonite is a very soft phyllosilicate mineral that typically forms in microscopic Crystals forming a clay. Clay minerals are hydrous Aluminium phyllosilicates, sometimes with variable amounts of Iron, Magnesium, Alkali metals Alkaline Illite is a non-expanding Clay -sized micaceous mineral Illite is a phyllosilicate or layered alumino-silicate The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution Chlorites are not always considered a clay, sometimes being classified as a separate group within the phyllosilicates. The silicate minerals make up the largest and most important class of rock-forming Minerals They are classified based on the structure of their silicate Ion group There are approximately thirty different types of "pure" clays in these categories, but most "natural" clays are mixtures of these different types, along with other weathered minerals.

Varve (or varved clay) is clay with visible annual layers, formed by seasonal differences in erosion and organic content. A varve is an annual layer of Sediment or Sedimentary rock. The word 'varve' is derived from the Swedish word varv whose Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind This type of deposit is common in former glacial lakes. A glacial lake is a Lake with origins in a melted Glacier. Glacial lakes can be green as a result of pulverized minerals ( Rock flour) that support

Quick clay is a unique type of marine clay indigenous to the glaciated terrains of Norway, Canada and Sweden. Quick clay, also known as Leda clay and Champlain Sea clay in Canada, is a unique form of highly sensitive Marine clay, with the tendency to Marine clay is a type of Clay found in coastal regions around the world Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. It is a highly sensitive clay, prone to liquefaction, which has been involved in several deadly landslides. A landslide is a geological phenomenon which includes a wide range of ground movement such as rock falls deep failure of slopes and shallow debris flows which can occur

Historical and modern uses

Clay layers in a construction site. Dry clay is normally much more stable than sand with regards to excavations.

Clays exhibit plasticity when mixed with water in certain proportions. When dry, clay becomes firm and when fired in a kiln, permanent physical and chemical reactions occur which, amongst other changes, causes the clay to be converted into a ceramic material. Pit firing is the oldest known method of firing Clay. Unfired pots are nestled together in a pit in the ground and are then covered with burnable materials such as wood shavings Kilns are thermally insulated chambers or Ovens in which controlled temperature regimes are produced The word ceramic is derived from the Greek word κεραμικός ( keramikos) It is because of these properties that clay is used for making pottery items, both practical and decorative. Pottery is the Ceramic ware made by potters It also refers to a group of materials that includes Earthenware, Stoneware Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware, stoneware and porcelain. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Earthenware is a common Ceramic material which is used extensively for Pottery tableware and decorative objects Stoneware a Vitreous or semivitreous ceramic ware of fine texture made primarily from nonrefactory fire clay Porcelain is a Ceramic material made by heating raw materials generally including Clay in the form of Kaolin, in a Kiln to temperatures Early humans discovered the useful properties of clay in prehistoric times, and one of the earliest artifacts ever uncovered is a drinking vessel made of sun-dried clay. Depending on the content of the soil, clay can appear in various colors, from a dull gray to a deep orange-red.

Clay tablets were used as the first writing medium, inscribed with cuneiform script through the use of a blunt reed called a stylus. A stylus (plural styli or styluses) is a Writing utensil. The word is also used for a computer accessory ( PDAs)

Clays sintered in fire were the first form of ceramic. Sintering is a method for making objects from powder, by heating the material (below its Melting point - solid state sintering until its particles adhere The word ceramic is derived from the Greek word κεραμικός ( keramikos) Bricks, cooking pots, art objects, dishware and even musical instruments such as the ocarina can all be shaped from clay before being fired. A brick is a block of Ceramic material used in Masonry construction laid using mortar. The ocarina ( is an ancient Flute -like Wind instrument. While several variations exist an ocarina is typified by an oval-shaped enclosed space with four to twelve Clay is also used in many industrial processes, such as paper making, cement production and chemical filtering. Paper is thin material mainly used for writing upon printing upon or packaging In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together In Chemistry and common usage a filter is a device (usually a membrane or layer that is designed Clay is also often used in the manufacture of pipes for smoking tobacco and marijuana. Tobacco is an Agricultural product recognized as an addictive drug processed from the fresh Leaves of plants in the genus Nicotiana. Cannabis, also known as marijuana or marihuana, or ganja (from Hindi / Sanskrit: गांजा gānjā hemp) is a

Clay, being relatively impermeable to water, is also used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage ('lining' the landfill, preferably in combination with geotextiles). Permeability in the Earth sciences (commonly symbolized as κ, or k) is a measure of the ability of a material (typically a rock or unconsolidated A dam is a barrier that divides waters. Dams generally serve the primary purpose of retaining water while other structures such as Floodgates, Levees For other uses see Water treatment and Land reclamation. A landfill, also known as a dump (and historically as Geotextiles are permeable Fabrics which when used in association with Soil, have the ability to separate filter reinforce protect or drain ^[3]

Recent studies have been carried out to investigate clay's adsorption capacities in various applications, such as the removal of heavy metals from waste water and air purification. Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the

Medical

A recent article in The Journal of Antimicrobial Chemotherapy found that certain iron-rich clay was effective in killing bacteria. ^[4]

See also

Footnotes

References

• Guggenheim, Stephen & Martin, R. Middle East Technical University ( METU; in Turkish, Orta Doğu Teknik Üniversitesi, commonly referred to as ODTÜ) is a public Ankara is the capital of Turkey and the country's second largest city after İstanbul. Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches T. (1995), “Definition of clay and clay mineral: Journal report of the AIPEA nomenclature and CMS nomenclature committees”, Clays and Clay Minerals 43: 255–256, <http://www.clays.org/journal/archive/volume%2043/43-2-255.pdf> 
• Clay mineral nomenclature American Mineralogist.

• Ehlers, Ernest G. and Blatt, Harvey (1982). 'Petrology, Igneous, Sedimentary, and Metamorphic' San Francisco: W. The City and County of San Francisco is the fourth most populous city H. Freeman and Company. ISBN 0-7167-1279-2.

• Hillier S. (2003) Clay Mineralogy. pp 139-142 In: Middleton G. V. , Church M. J. , Coniglio M. , Hardie L. A. and Longstaffe F. J. (Editors) Encyclopedia of sediments and sedimentary rocks. Kluwer Academic Publishers, Dordrecht.

External links

• The Clay Minerals Group of the Mineralogical Society
• Historical information about the clays of North Staffordshire, UK
• Information about clays used in the UK pottery industry