Magnesium+silicate

Magnesium Silicate MgSiO3 is a silicate salt of magnesium. The most common forms found in nature are asbestos and talc. magnesium silicate is used in the formation of talcum powder, which is used widely in a variety of industries such as, paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics.



This is a white, odorless, finely divided powders formed by the precipitation reaction of water soluble sodium silicate and a water soluble magnesium salt. The composition of the precipitate depends on the ratio of components in the reaction medium, the addition of the correcting substance, and the way in which they are precipitated.



Formation
Talc is a [|metamorphic mineral] resulting from the metamorphism of magnesian minerals such as [|serpentine], [|pyroxene] , [|amphibole] , [|olivine] , in the presence of carbon dioxide and water. This is known as //talc carbonation// or //steatization// and produces a suite of rocks known as [|talc carbonates]. Talc is primarily formed via hydration and carbonation via the following reaction; // [|serpentine] + [|carbon dioxide] → talc + [|magnesite] + [|water] //2 Mg3Si2O5(OH)4 + 3CO2 → Mg3Si4O10(OH)2 + 3 MgCO3 + 3 H2O Talc can also be formed via a reaction between dolomite and silica, which is typical of [|skarnification] of dolomites via silica-flooding in contact metamorphic aureoles; // [|dolomite] + [|silica] + water → talc + [|calcite] + carbon dioxide//3 CaMg(CO3)2 + 4 SiO2 + H2O → Mg3Si4O10(OH)2 + 3 CaCO3 + 3 CO2 Talc can also be formed from magnesian chlorite and quartz in [|blueschist] and [|eclogite] metamorphism via the following [|metamorphic reaction] : // [|chlorite] + [|quartz] → [|kyanite] + talc + water// In this reaction, the ratio of talc and kyanite is dependent on [|aluminium] content with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as [|phengite], [|garnet] , [|glaucophane] within the lower [|blueschist facies]. Such rocks are typically white, friable, and fibrous, and are known as [|whiteschist]. Talc is a tri-octahedral layered mineral; its structure is similar to that of [|pyrophyllite], but with [|magnesium] in the octahedral sites of the composite layers.