Abstract:
The term clay can be interpreted in many ways depending on the point of view of the interpreter. Geologists, mineralogists, soil scientists and chemists approach clay from very different perspectives. Historically the term ‘clay was referred to soil fraction of < 2 nm in size irrespective of their crystallinity and composition. A more recent definition of clay is much more precise. According to Encyclopaedia Britannica, clay or clay mineral is referred to very fine mineral fragments or particles (< 2 nm) composed mostly of hydrous layered silicates of aluminium, though occasionally containing iron, alkali metals or alkaline earth metals.(1)
The usage of clay in human civilization dates back to antiquity. The first known application of clay in prehistoric times was as clay bricks. Even in the ancient civilizations of Cyprus and Greece clays were used as bleaching material and as soaps for removing grease and stains 5000 years ago. Mankind has come a long way from then regarding the applications of clays. In modern civilization clays find their use in a tremendous number of places. From toothpaste, pencils (laponite), paint and plastic additives (kaolinite), household ceramics (kaolinite) to the cores of daM.S. or as a barrier against toxic and radioactive leakage (bentonite) clays are literally everywhere.
