Talc and Ground Soapstone

Abstract

Industrial talcs and ground soapstones both include earth materials of different chemical and mineral compositions. In general, the industrial talcs are composed of silicates that contain appreciable amounts of magnesia. Generally talc, the mineral, is a predominant or at least common constituent. Talc, the mineral, is a hydrous magnesium silicate, with a suggested theoretical formula H₂Mg₃(SiO₃)₄ or H₂O.3MgO.4SiO₂, which postulates 63.5 pct SiO₂, 31.7 pct MgO, and 4.8 pct H₂O. Actually different single grains or leaves of pure talc have variations in water content ranging from 3.5 pct to more than 7 pct, as well as slight differences in the proportions of MgO and SiO₂.

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