Species and characteristics of clay

Alumino silicate clay is dominated by rocks, such as feldspar pegmatite granite, porphyry, gneiss, etc. The long-term weathering, and often through water transport and deposition are too many fine mineral mixture, its main chemical composition of SiO2, Al2O3, and water of crystallization. With different geological formation conditions, may also contain small amounts of alkali metal oxides, alkaline earth metal oxides and coloring oxides.

Varieties and uses a lot of clay, often according to mineralogical, geological origin, chemical composition, physical properties or industrial uses clay classification.

1. More clay minerals in the main types can be divided kaolin clay series, smectite and illite clay series. 
2. According generation, the clay can be divided into the native clay (Primary clay) and secondary clay (Secondary clay), the native clay is the generation after feldspar weathering of silicate hydrous kaolin and other minerals, quartz, etc., is not completely broken weathered residual debris in situ, and soluble salts were dissolved; secondary raw clay is a former clay transferred under dynamic conditions to the rest of the natural crystalline clay again.
3. According to the plasticity of clay can be divided into soft clay (strong plasticity clay), semi-soft clay (clay plasticity) and hard clay (clay plasticity weak), mostly secondary soft clay clay, because fine particles dispersed degree, so plasticity; hard clay and more by diagenesis ancient community, and the lack of free water is not easy to dip into the bulk, plasticity poor.

Some Western industrialized countries often comes down to the clay six categories, namely: Kaolin (Kaolin), fire clay (Fire clay), ball clay (Ball clay), bentonite (Bentonite), bleaching earth (Fuller, s earth) and the general clay (Common) where bentonite, fuller's earth and ordinary clay mainly composed of montmorillonite, illite and chlorite, etc., poor fire resistance.

Classification and habits at home and abroad, the refractory clay Category: kaolin, ball clay and fire clay. Natural clay minerals according to the above classification is not always a sharp distinction between, and sometimes a clay can contain a variety of clay, but the performance is also superimposed on each other, such as mineral composition and chemical composition of many hard clay and kaolin are very close; many balls soft refractory clay and the clay of the same physical properties. Regardless of how the kind of clay, clay determine its performance properties.