talc

talc
/talk/, n., v., talcked or talced /talkt/, talcking or talcing /tal"king/.
n.
1. Also, talcum /tal"keuhm/. a green-to-gray, soft mineral, hydrous magnesium silicate, Mg3(Si4O10)(OH)2, unctuous to the touch, and occurring usually in foliated or compact masses, used in making lubricants, talcum powder, electrical insulation, etc.
v.t.
3. to treat or rub with talc.
[1595-1605; < ML talcum < Ar talq mica < Pers talk]

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Common silicate mineral that is distinguished from almost all other minerals by its extreme softness.

Its soapy or greasy feel accounts for the name soapstone, given to compact aggregates of talc with other rock-forming minerals. Soapstones have been used since ancient times for carvings, ornaments, and utensils. Resistant to most reagents and to moderate heat, they are especially suitable for sinks and countertops. Talc is also used in lubricants, leather dressings, toilet and dusting powders, and certain marking pencils; as a filler in ceramics, paint, paper, roofing materials, plastic, and rubber; as a carrier in insecticides; and as a mild abrasive in the polishing of cereal grains.

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      common silicate mineral that is distinguished from almost all other minerals by its extreme softness (it has the lowest rating [1] on the Mohs scale of hardness). Its soapy or greasy feel accounts for the name soapstone given to compact aggregates of talc and other rock-forming minerals. Dense aggregates of high-purity talc are called steatite.

      Since ancient times, soapstones have been employed for carvings, ornaments, and utensils; Assyrian cylinder seals, Egyptian scarabs, and Chinese statuary are notable examples. Soapstones are resistant to most reagents and to moderate heat; thus, they are especially suitable for sinks and countertops. Talc is also used in lubricants, leather dressings, toilet and dusting powders, and certain marking pencils. It is used as a filler in ceramics, paint, paper, roofing materials, plastic, and rubber; as a carrier in insecticides; and as a mild abrasive in the polishing of cereal grains such as rice and corn.

      Talc is found as a metamorphic mineral in veins, in foliated masses, and in certain rocks. It is often associated with serpentine, tremolite, forsterite, and almost always with carbonates (calcite, dolomite, or magnesite) in the lower metamorphic facies. It also occurs as an alteration product, as from tremolite or forsterite.

       Silicate mineralsOne of the remarkable features of talc is its simple, almost constant composition; talc is a basic magnesium silicate, Mg3Si4O10(OH)2. Unlike other silicates, even closely related ones, talc appears to be unable to accept iron or aluminum into its structure to form chemical-replacement series, even though an iron analog of talc is known, and the structurally related chlorite forms at least a partial series between iron and magnesium end-members. Talc is distinguishable from pyrophyllite chemically and optically. For detailed physical properties, see silicate mineral (table (Silicate minerals)).

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Universalium. 2010.

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  • talc — s.n. Silicat natural hidratat de magneziu, de culoare albă verzuie, unsuros şi moale la pipăit, folosit în industria farmaceutică, textilă etc. – Din fr. talc. cf. it. t a l c o , germ. T a l k . Trimis de LauraGellner, 13.09.2007. Sursa: DEX 98… …   Dicționar Român

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  • Talc — Talc, n. [F. talc; cf. Sp. & It. talco, LL. talcus; all fr. Ar. talq.] (Min.) A soft mineral of a soapy feel and a greenish, whitish, or grayish color, usually occurring in foliated masses. It is hydrous silicate of magnesia. {Steatite}, or… …   The Collaborative International Dictionary of English

  • talc — (n.) 1580s, from M.Fr. talc, probably from Sp. talco and M.L. talcum talc (ealy 14c.), both from Arabic talq, from Pers. talk talc. It was applied by the Arab and medieval writers to various transparent, translucent and shining minerals such as… …   Etymology dictionary

  • talc — s. m. Sorte de pierre, qui se trouve dans les carrieres de plastre, & qui est transparente comme le verre, & se leve par feüilles. Le talc ne se calcine point, on met du talc, des feüilles de talc sur les mignatures pour les conserver. les… …   Dictionnaire de l'Académie française

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  • talc — [talk] n. [Fr < Ar ṭalq] 1. a soft, light colored, monoclinic mineral, Mg3Si4O10 (OH) 2, with a greasy feel, used to make talcum powder, lubricants, etc.; magnesium silicate: see MOHS SCALE 2. short for TALCUM (POWDER) vt. talcked or talced,… …   English World dictionary

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