Kaolin is mainly found as the product of chemical effect on air (weathering) on feldspars. Sedimentary processes transport kaolin and separate it from other sedimentary materials so it is deposited as pure substrates. Kaolinite is extracted from these substrates and is used without further purification in some cases. It is obtained as the product of silicate alteration due to hot groundwater in or in the vicinity of sulfur veins or in hot springs and geysers.
Kaolin is crystallized in the triclinic system as flat crystals, worm-like sets, clay-like masses and particles dispersed in sedimentary rocks.Wet kaolin is greasy and moldable. Pure kaolin is found in white but impure kaolin is found in bisque and greyish colors. Kaolin sheets are transparent, but kaolin sets are opaque. It is obtained as very thin extended layers or as a result of rock weathering. The specific gravity and hardness of kaolin are 2.6 and 2 Mohs, respectively.
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