Mineral Occurrence Kaolinite clay occurs in abundance in soils that have formed from the chemical weathering of rocks in hot, moist climates—for example in tropical rainforest areas. Kaolinite is one of the most common minerals; it is mined, as kaolin, in Malaysia, Pakistan, Vietnam, Brazil, Bulgaria, Bangladesh, France, the United Kingdom, Iran, Germany, India, Australia, Korea, the People’s Republic of China, the Czech Republic, Spain, South Africa, and the United States. Formation Formed by repeating layers of stacks of 1 silica sheet (tetrahedral) and 1 alumina silica sheet (gibbsite). It is joined by hydrogen bonds. Since hydrogen bonds is very strong, it prevents hydration. As a result, layers can stack up to make large crystals, up to 70 to 100 layers thick. Kaolinite is formed by chemical weathering or hydrothermal alteration of aluminosilicate minerals. Thus, rock rich in feldspar commonly weather to kaolinite. In order to form, ions like Na, K, Ca, Mg, and Fe must first be leached away by the weathering alteration process. Tis leaching is favored by acidic conditions (low pH). Granitic rocks, because they are rich in feldspar, are common source for kaolinite. Crystallography Crystal system : Triclinic Class (H-M): 1-Pedial Space Group: P1 Cell Parameters: a = 5.13 A, b = 8.89 A, c = 7.25 A apha, 91.8°,: beta, 104.5°; gamma, 90.016° Crystal Structure (pictures) Differences (descriptions) Kaolinite also includes dickite and nacrite; formed by the decomposition of orthoclase feldspar (e.g. in granite); kaolin is the principal constituent in china clay. Smectites or Montmorillonites also includes bentonite and vermiculite; formed by the alteration of mafic igneous rocks rich in Illite also includes glauconite (a green clay sand) and are the commonest clay minerals; formed by the decomposition of some micas and feldspar; predominant in marine clays and shales. Note: Kaolinite, illite and smectite pictures, kindly search nalang. Thanks Physical Properties Uses 1. China, Porcelain and Tableware Kaolinite is the main, raw material used in traditional pottery ceramics. The powder is mixed with clay and other materials in order to make it malleable. 2. Paper Industry It serves as a paper coating which improves appearance by contributing to brightness, smoothness and gloss. It used as a filler, it makes the paper whiter and smoother to print sharper image on. 3. Toothpaste Kaolin particles are used as a sort of polishing sand to smooth your teeth and ship away plaque. 4. Pharmaceutical Used in many pharmaceutical applications as excipient or active ingredient because it exhibits excellent physical, chemical and surface physiochemical properties 5. Rubber The composition of the weight percent range of clay (5-35%) to rubber latex (100%) was feasible to produce durable rubber-clay composite sheets product. Good mechanical reinforcement. Low moisture pickup. 6. Paints Color Performance- improve pigment efficiency, it consequently improves color, strength, and thus influences color hue Glass Performance- gloss is the function of filling rate and fineness of kaolin. Opacity Performance- fine hydrous grades improve pigment efficiency in enamels while calcined grades increase porosity in architectural paints. Gel strength- improves in-can stability and avoid settling of pigment or coarse mineral filler. Low shear viscosity- provides excellent applicability properties such as brushers and rollers 7. Adhesive, Sealants and Caulks Use as economic and functional extender in an acrylic emulsion improving cohesive strength Facts Kaolinite is a clay mineral. It is part of the group industrial minerals 𝐴𝑙2 𝑆𝑖2 𝑂5 (𝑂𝐻)4 Kaolinite is a common 1:1 dioctahedral phyllosilicate (clay) mineral found in soils across the world Being a 1:1 clay mineral, each kaolinite layer has one silica tetrahedral sheet and one alumina octahedral sheet Mined as kaolin Origin: Gaoling Mine (Kauling Mine), Gaoling village, Ehu town, Fuliang Co., Jingdezhen, Jiangxi, China References Adam, E. (2019). Minerals Education Coalition-Kaolinite. Retrieved from: https://mineralseducationcoalition.org/minerals-database/kaolinite/. Retrieved last April 9, 2019 Amethyst G. (2009). KAOLINITE (Aluminum Silicate Hydroxide). http://www.galleries.com/Kaolinite. Retrieved last April 9, 2019 Retrieved from: Murray, H. (1960). Industrial Applications of Kaolin. Retrieved from: https://pdfs.semanticscholar.org/1ac6/5687f6ac7014cd44dc1fc5ee359242c349f7. Retrieved last April 8, 2019. Barthelmy, D. (2014). Kaolinite Mineral Data, Clays and Clay Miner. Retrieved from: http://webmineral.com/data/Kaolinite.shtml#.XMXWnhnmhAh. Retrieved last April 9, 2019. Barak, P. (2005). The Virtual Museum of Minerals and Molecules. Retrieved from: https://virtualmuseum.soils.wisc.edu/display/kaolinite/. Retrieved last April 9, 2019.
