Clay

claysblue clayammonia-rich claysclay-bearing unitargilpipeclayargillaceousclay soilclay soilsLondon Clay
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO 2 ), metal oxides (Al 2 O 3, MgO etc.) and organic matter.wikipedia
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Silt

siltysilt depositdesilted
Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. Mixtures of sand, silt and less than 40% clay are called loam.
Silt is granular material of a size between sand and clay, whose mineral origin is quartz and feldspar.

Sedimentology

sedimentologicalsedimentologistsedimentary geology
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.
Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation (erosion and weathering), transport, deposition and diagenesis.

Weathering

weatheredchemical weatheringweather resistant
Clay minerals typically form over long periods of time as a result of the gradual chemical weathering of rocks, usually silicate-bearing, by low concentrations of carbonic acid and other diluted solvents.
The various agents act in concert to convert primary minerals (feldspars and micas) to secondary minerals (clays and carbonates) and release plant nutrient elements in soluble forms.

Soil

soilsdirtsoil moisture
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO 2 ), metal oxides (Al 2 O 3, MgO etc.) and organic matter.
Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates: sand, silt, and clay.

Illite

hydromicaAvaliteillite clay
Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite, illite, and chlorite.
Illite is a group of closely related non-expanding clay minerals.

Kaolinite

kaolinchina claykaolin clay
Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite, illite, and chlorite.
It is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar.

Marine clay

(marine) clayglaciomarine claysmarine soil
Quick clay is a unique type of marine clay indigenous to the glaciated terrains of Norway, Canada, Northern Ireland, and Sweden.
Marine clay is a type of clay found in coastal regions around the world.

Sedimentary rock

sedimentarysedimentary rockssediments
Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit.
Most geologists use the Udden-Wentworth grain size scale and divide unconsolidated sediment into three fractions: gravel (>2 mm diameter), sand (1/16 to 2 mm diameter), and mud (clay is

Atterberg limits

plasticity indexLiquid LimitPlastic limit
Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits.
The Atterberg limits can be used to distinguish between silt and clay, and to distinguish between different types of silts and clays.

Pottery

potterceramicspotters
Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing. However, when dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur.
Pottery is the process of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard, durable form.

Clay minerals

smectiteclay mineralclay
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO 2 ), metal oxides (Al 2 O 3, MgO etc.) and organic matter. Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite, illite, and chlorite.
Clays form flat hexagonal sheets similar to the micas.

Silicate minerals

silicate mineralphyllosilicatephyllosilicates
Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.

Loam

loamysandy loamsilt loam
Mixtures of sand, silt and less than 40% clay are called loam.
Loam is soil composed mostly of sand (particle size > 63 µm), silt (particle size > 2 µm), and a smaller amount of clay (particle size < 2 µm).

Kiln

kilnsfiredbrick kiln
However, when dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur.
A kiln ( or, originally pronounced “kill", with the “n” silent) is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles and bricks. Various industries use rotary kilns for pyroprocessing—to calcinate ores, to calcinate limestone to lime for cement, and to transform many other materials.

Ceramic

ceramicsceramic materialsceramicist
These changes convert the clay into a ceramic material. Clays sintered in fire were the first form of ceramic.
The earliest ceramics made by humans were pottery objects (i.e. pots or vessels) or figurines made from clay, either by itself or mixed with other materials like silica, hardened and sintered in fire.

Brick

red brickbricksbrickmaking
Bricks, cooking pots, art objects, dishware, smoking pipes, and even musical instruments such as the ocarina can all be shaped from clay before being fired.
Traditionally, the term brick referred to a unit composed of clay, but it is now used to denote rectangular units made of clay-bearing soil, sand, and lime, or concrete materials.

Earthenware

earthen potearthenwaresblack and red ware
Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware, stoneware, and porcelain.
The Combined Nomenclature of the European Communities describes it as being made of selected clays sometimes mixed with feldspars and varying amounts of other minerals, and white or light-colored (i.e., slightly greyish, cream, or ivory).

Sand

sand grainsandybeach sand
Mixtures of sand, silt and less than 40% clay are called loam.

Bentonite

bentoniticbentonite claysodium bentonite
Until the late 20th century, bentonite clay was widely used as a mold binder in the manufacture of sand castings.
Bentonite is an absorbent aluminium phyllosilicate clay consisting mostly of montmorillonite.

Sintering

sinteredsinterPressureless sintering
Clays sintered in fire were the first form of ceramic.
Some ceramic raw materials have a lower affinity for water and a lower plasticity index than clay, requiring organic additives in the stages before sintering.

Tobacco pipe

pipesmoking pipepipes
Bricks, cooking pots, art objects, dishware, smoking pipes, and even musical instruments such as the ocarina can all be shaped from clay before being fired.
The bowls of tobacco pipes are commonly made of briar wood, meerschaum, corncob, pear-wood, rose-wood or clay.

Colloid

colloidscolloidalcolloid chemistry
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.
Various types of colloids are recognised: inorganic colloids (e.g. clay particles, silicates, iron oxy-hydroxides), organic colloids (humic and fulvic substances).

Medicinal clay

healing clayclay as medicinekaoline poultice
Traditional uses of clay as medicine goes back to prehistoric times.
Indigenous peoples around the world still use clay widely, which is related to geophagy.

Cuneiform

cuneiform scriptAkkadian cuneiformSumerian cuneiform
Scribes wrote by inscribing them with cuneiform script using a blunt reed called a stylus.
Originally, pictographs were either drawn on clay tablets in vertical columns with a sharpened reed stylus or incised in stone.

Armenian bole

boleArmenic bolebole armoniac
An example is Armenian bole, which is used to soothe an upset stomach.
Armenian bole, also known as bolus armenus or bole armoniac, is an earthy clay, usually red, native to Armenia.