Quimica, Chemical: TALCO / TALC

Talco

Fórmula Mg3Si4O10(OH)2 Densidad 2.7-2.8 g/ml
Dureza 1 en la escala de Mohs Sistema cristalino Triclínico
Color Blanco a gris verdoso Brillo Mate Raya Blanca
Clivaje Perfecto

Talco: El talco (nombre derivado del árabe tal q) es un mineral de color blanco a gris verdoso perteneciente al grupo de los silicatos. En la escala de Mohs se toma como patrón de la menor dureza posible, asignándosele convencionalmente el valor 1. Al tacto resulta tan grasiento o jabonoso que puede rayarse con la uña.

Yacimientos: El talco suele aparecer de forma masiva (forma también llamada esteatita) y raras veces en cristales bien formados. Se forma por metamorfosis de silicatos de magnesio como la olivina, piroxeno o anfíbol.
Los principales productores son Estados Unidos, China y la Unión Europea de dónde proceden más de dos tercios de la producción mundial.

Importancia industrial: Se utiliza en diversas aplicaciones. En forma de polvo se utiliza como relleno en la fabricación de papel y cartulina, para lacas y pinturas, en la industria cerámica, como aditivo de gomas y plásticos, así como para prevenir irritaciones de la piel y para hidratar ésta. Por su resistencia a elevadas temperaturas se utiliza en la fabricación de materiales termorresistentes. También es la base de muchos polvos en la cosmética.
Incluso se utiliza en la industria alimentaria como E553b.

Para comprar un talco, recuerde, lo importante es el tamaño de partículo, el grado de blancura y la aplicación que al final desea para darle. Consultas a lordserer@gmail.com

English version: Talc (derived from the Persian via Arabic talq) is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. In loose form, it is the widely used substance known as talcum powder. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. It is sectile and very soft, with a hardness of 1 (Talc is the softest of the Mohs' scale of mineral hardness, and can be easily scratched by a fingernail). It has a specific gravity of 2.5–2.8, a clear or dusty luster, and is translucent to opaque. Its colour ranges from white to grey or green and it has a distinctly greasy feel. Its streak is white.

Talc is a metamorphic mineral resulting from the metamorphism of magnesian minerals such as pyroxene, amphibole, olivine and other similar minerals 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 of serpentine, via the following reaction;
Serpentine + Carbon Dioxide → Talc + Magnesite + Water

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

Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism via the following metamorphic reaction:
Chlorite + Quartz → Kyanite + Talc + H2O
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.[1]

A coarse grayish-green high-talc rock is soapstone or steatite and has been used for stoves, sinks, electrical switchboards, etc. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. Talc is used in baby powder, an astringent powder used for preventing rashes on the area covered by a diaper (see diaper rash). Most tailor's chalk is talc, as is the chalk often used for welding or metalworking.
Talc is also used as food additive or in pharmaceutical products. In medicine talc is used as a pleurodesis agent to prevent recurrent pneumothorax. In the European Community the additive number is E553b.
Recently it has come into popularity as a base for cocaine for several reasons. The first, and most common though, is that its chemical properties interfere with the sense of smell in most dogs, causing the drug to be next to undetectable by drug sniffing dogs.

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