clays are derived from the minerals in rocks by chemical decomposition. they are the end product of weathering . there are different families of clays depending on chemical composition and crystal structure and there are various clays in each family. soils are mixtures of rocks, minerals, and clays. like clays, soils are grouped but by texture and mineral composition rather than by chemistory and crystallography. given enough time a soil may break down to one or more clays but a pure clay will never break down to soil.
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