talc

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talc A member of the 2:1 phyllosilicates (sheet silicates) with composition Mg6[Si4O10]2(OH)4; sp. gr. 2.58–2.83; hardness 1 (it has the lowest hardness on Mohs's scale of hardness); monoclinic; rare crystals are tabular, often massive; white to green; cleavage perfect hardness; massive talc (soapstone or steatite) can be formed during the low-grade metamorphism of siliceous dolomites; and as a secondary mineral during hydrothermal alteration of ultrabasic igneous rocks along shear planes. It is associated with serpentization with serpentine changing to talc and magnetite by addition of CO2. It is used extensively as a mineral filler.

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talc / talk/ • n. talcum powder. ∎  a white, gray, or pale green soft mineral with a greasy feel, occurring as translucent masses or laminae and consisting of magnesium hydroxyl silicate. • v. (talced, talc·ing) [tr.] powder or treat (something) with talc. DERIVATIVES: talc·ose / ˈtalkōs/ adj. ( Geol. ). talc·y / ˈtalkē/ adj.

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talc (hydrous magnesium silicate, Mg3Si4O10(OH)2). It occurs as rare tabulate crystals in a monoclinic system and as masses. It is used as base for talcum powder and in ceramics. Hardness 1; r.d. 2.6.

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talccalque, talc •catafalque •elk, whelk •bilk, ilk, milk, silk •Liebfraumilch • buttermilk • volk •bulk, hulk, skulk, sulk

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talc species of translucent or shining minerals, e.g. mica. XVI. — F. talc or medL. talcum (whence talcum XVI) — Arab. ṭalḳ — Pers. talk.

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talc (tal'k) n. a soft white powder consisting of magnesium silicate, used as a dusting powder.