TALC, in mineralogy, is divided into three sub-species, viz. 1.The earthy talc, which is of a greenish white colour, com pesecl of glimmering pearly, small scaly parts: it soils a little, and feels rather greasy. It occurs in the tin mines near Freyburg, in Saxony. 2. Common Vene tian talc is of an apple green, which passes on one side into greenish white, and• even into silver white ; on the other, into asparagus green. ' It is massive, dis seminated, and in extremely delicate, crystals. It is splendent and shining : feels very greasy, and is easy frangible. It is infusible before the blow-pipe, with out addition ; and its constituent parts arc, Magnesia 44 Silex 50 Alumina 6 100 This is confounded with mica, from which it is, however, distin guished by want of elasticity ; by its greasy feel, and colour. 14 is almost en tirely confined to the primitive mountains, where it occurs in beds, imbedded,. in ser
pentine, and also in veins. It abounds rn the mountains of Tyrol and Salzburg, hence it is brought to Venice, and on that account has obtained the naive of Venetian talc. It is employed as a basis for coloured crayons, and for the finest rouge.
3. Indurated talc is of a greenish colour: it occurs massive ; lustre shining, passing to glistening, and is pearly, feels rather greasy. It occurs in primitive mountains, where it forms beds in clay, slate,' and serpentine. It is thought to be an intermediate link between steatite and pot-stone, which see. It is found in the Alps, in Stiria, and in Austria, and Hungary : also in some parts of Scotland the constituent parts. are, Magnesia 38.54 Silica 38.12 Alumina 6.66 Lime 041 Iron 15.02 . 98.75 Loss 1.25 • 100.00