TALC • DICTIONARY ONE.COM • Definition of Talc

... carbonate it occurs in large quantity as magnesite (MgCO{3}), which is the chief source of magnesia. Mixed with carbonate of lime, it forms magnesian limestone and dolomite. It is present in larger or smaller quantity in most silicates; and the minerals, serpentine, talc, steatite and meerschaum are essentially hydrated silicates of magnesia. Soluble magnesian salts occur in many natural waters; more especially the sulphate and the chloride. Kieserite (MgSO{4}.H{2}O) occurs in quantity ...

— A Textbook of Assaying: For the Use of Those Connected with Mines. • Cornelius Beringer and John Jacob Beringer