talc

talc, mineral ranging in color from white through various shades of gray and green to the red and brown of impure specimens, translucent to opaque, and having a greasy, soapy feel. It is a hydrous silicate of magnesium, Mg₃Si₄O₁₀(OH)₂, and usually contains small quantities of nickel, iron, and aluminum as impurities. It occurs commonly in folia (thin layers), but is also found in coarsely granular, finely granular, or cryptocrystalline masses. Soapstone, or steatite, is a massive, granular form of talc. French chalk is a fine-grained variety. Talc is usually associated with chlorite schists, serpentine, dolomite, and other metamorphic rocks; it is apparently a secondary mineral formed by the alteration of other magnesium silicates. There are important deposits of talc in Austria, Italy, France, and Canada and in the United States in California, North Carolina, Texas, Georgia, and Montana. Talc is used in making paper (as a filler), paints, face and talcum powder, soap, fireproof roofing, foundry facings, lubricants, linoleum and oilcloth, electrical insulation, and pottery.

---

talc

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.

---

talc

a white, grey, brown, or pale green mineral, found in metamorphic rocks. It is used in the manufacture of talcum powder and electrical insulators. Composition: hydrated magnesium silicate. Formula: Mg₃Si₄O₁₀(OH)₂. Crystal structure: monoclinic

---

talc [talk]

(mineralogy)

Mg₃Si₄O₁₀(OH)₂A whitish, greenish, or grayish hydrated magnesium silicate mineral crystallizing in the monoclinic system; it is extremely soft (hardness is 1 on Mohs scale) and has a characteristic soapy or greasy feel.