Talc (magnesium hydrate silica) is a soft, crushable mineral made of soft colloids with a soapy feel. It has a three-layer structure, consisting of two tetrahedral silica layers and an octahedral layer. All octahedral layers are filled with magnesium ions. The bond between talc sheets is weaker than that of kaolinite. Therefore, talc is more slippery. In its pure form, it is white; however, it may take the colors gray, green, brown, or red due to impurities. Talc is the product of the hot-water transform of alkaline stones and the transformation of dolomite persilica.


In monoclinic system the mineral is crystalized as flat crystals sheet, radial, concentrated masses. The effect line is white, ranging from semi-transparent to transparent. Large sheets have a pearly shine. Talc sheets are flexible, but are not tensile like mica. Its facet is perfect from one view, with irregular breaking. It has a specific weight of 2.8 and hardness of 1 mohs. Talc also has some iron, calcium, and aluminum content.


Since ancient times, talc has been a valuable substance for producing cosmetics. Today, it is used in cosmetics, paper coatings, paints and rubbers (as filler), electric insulant in molds, in heater components, chemical dishes, and ceramic raw material, in making anti-acid holes, and tabletop finish in chemical laboratories.


Mica is known as muscovite glass. Muscovite (aluminum potassium hydrate silica) is the most common form of mica. It is a derivative of ideal talc and pyrophyllite structure in environments containing ions of aluminum, potassium, sodium, or calcium. That is, for ¼ of tetrahedral silica, aluminum and potassium are placed between the sheets to maintain electric non-conductivity. The bond between muscovite sheets is weaker than that that between particles, indicated by the one-sided facet. However, their bond is stronger than that of pyrophyllite bonds, therefore muscovite does not feel greasy. Muscovite is found in granite and persilicate stones, and many kinds of metamorphic rocks. It is also one of the main components of schist sediments.


The rock is crystalized in a monoclinic system as flat crystals and mostly fake hexagonal forms. It is distributed as thick sheets in igneous rocks, as stripes in schist and gneiss, as well as clay in sediment rocks. It has a perfectly one-sided facet and can be separated as sheets with corrugated edges. It is tensile and strong. It is colorless, grey, light green, brown, yellow, orange, or purple, with a glossy or pearly shine. It may be opaque to semi-transparent and as thin sheets, is transparent. It has a hardness of 2–3 mohs and a specific weight of 2.7–3.1.


It is used as electric insulant in electric tools, airplane spark plugs, irons, brake pads, etc.


Kaolinite is the pure form of soil (hydrate aluminum silica). It comes in three variants: kaolinite, necrite, and dickeite, with all three having the same formula. It is found in soil masses with a dark shine. It consists of a double-layer sheet consisting of a layer of tetrahedral silica (with hydroxyl ions) and an octahedral layer of aluminum. Aluminum, oxygen, and hydroxyl ions of the tetrahedral layer are at one side, while hydroxyl ions are at the other side. The bond between sheets is quite weak. There are hydrogen bonds between the hydroxyl ions of a sheet and oxygen ions of the neighboring sheet. The mineral loses water at high temperatures and becomes refractory.


It is mostly a chemical product of air action on feldspars. Sedimentation processes transfer and separate it from other sediments, depositing it as pure beds. Kaolinite is then extracted from said beds without the need for treatment for different applications. It is a product of silica transformation due to hot groundwater streams in sulfur branches or in their proximity, as well as hot water springs and geysers.


It is used in pharmaceutics, fireproof bricks, china plates and ceramics as the whitening agent. In china utensils and chemical dishes, in water faucets, tubes, and tube lamps, accessories, coating of furnaces, electric insulators, color filler, coarse powders in rubber, sanding material, coating of clay dishes, and absorption agent in oil treatment. kaolinite is used in paints as a neutral and colored colloid agent.

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