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Talc

soapstone, mineral, massive and paper

TALC, one of the commonest and most important of the non-metallic minerals. It is usually massive or foliated, the laminae being flexible but not elastic. It is number one in Mohs scale of hardness, and like most very soft minerals it has a greasy feel. Its lustre is pearly and glimmering, and its usual colors are green, gray or white. Foliated varieties are often quite transparent, while the massive is translucent. It is of average specific gravity, about 2.7. It is acid magnesium silicate, HiMg,Si4012. Talc, like the related mineral ser pentine, is of secondary origin, having been formed by the alteration of various magnesian minerals such as tremolite, pyroxene and en statite. It occurs in metamorphic rocks all over the world, being the most prominent mineral in the rock known as talcose schist, and sometimes forms extensive beds, occurring thus in most of the Atlantic Coast states. Although very soft, it is almost indestructible, not being attacked by acids nor injuriously affected by intense heat. Its common, massive form, popularly known as "soapstone," is the °steatite° of mineralogy. Some soapstone is, however, a massive pyro phyllite (q.v.) and the term soapstone is applied loosely by miners to almost any soft rock or mineral with a greasy feel. Talc is used in the arts either powdered as Maur talc," or in sawed pieces. Flour talc is employed as a base for fireproof paints, in boiler and steampipe coverings, and foundry facings, for electric in sulators, in the manufacture of dynamite, and of wall papers to which it imparts a glossy surface; it is very extensively used in the manu facture of toilet powders, and cheap soaps, for dressing leathers and skins, and as a base for lubricants. About half a million dollars' worth

of "fibrous talc) is produced annually in the single county of Saint Lawrence in New York. This material is a mixture of talc and fibrous tremolite and is used in making paper. When ground the fibres cause the retention of the flour talc in the paper pulp, thus adding ma terially to the strength and weight of the paper. The supply of pure, compact soapstone, the most valuable variety of talc, comes largely from western, North Carolina and Virginia. It is savved into slate pencils and crayons and is manufactured into the tips of gas burners. The chief uses of soapstone are for stationary wash tubs, sinks, acid tanks, hearth-stones, fire bricks, mantels, griddles and many other articles of everyday use. ((French chalk" is a fine-granular talc used as a crayon by tailors. In China and Japan a fine compact talc is carved into various ornaments, household gods and pagodas, though considerable of the material thus used is agal matalite (q.v.) or pyrophyllite. See MINERAL PRODUCTION OF THE UNITED STATES.