Soapstone or Steatite or Talc is an alteration product of original or secondary Magnesium minerals. Talc is hydrous Magnesium Silicate and its chemical composition would correspond to 63.5% Silica (Si02), 31.7% Magnesia (MgO) and 4.8% water (H20). In nature, chemically pure Talc is very rare; it has some contaminations. Talc has a greasy or soapy feel and Pure Talc is characterized by extreme softness. Talc has good luster or sheen, high slip or lubricating power, good hiding power and ability to absorb specific types of oils and grease. Talc is inert to most chemical reagents, although it exhibits a marked alkaline pH of 9-9.5. It has low electrical and chemical conductivity.
Talcum Powder is widely used in many industries as a filler/extender and in other industrial applications due to its natural physical and chemical properties and relatively low price.
Talc Powder is used in industrial applications because of its lamellar platy nature, softness, whiteness, hydrophobic features, atmosphere & acid resistance, high thermal strength, chemical inertness, high dielectric strength, high melting point and absorption features. Particle size distribution is a critical parameter in most Talc Applications. Talc for paints, paper, plastics and cosmetics (with whiteness ranging from 80% to 98% with fineness up to 800 meshes with varying calcium percentage, ranging from 0.5 to 15%).
Talc is an important industrial mineral. Its resistance to heat, electricity and acids make it an ideal surface for lab counter tops and electrical switchboards. The Talc is also an important filler material for paints, rubber and insecticides. Even with all these uses, most people only know talc as the primary ingredient in talcum powder. Mineral specimens are not very common as it does not form very large crystals. However, it often replaces other minerals on an atom by atom basis and forms what are called pseudo morphs (false shape). The talc takes the form of the mineral it replaces. A specimen of what looks like milky quartz is quite a surprise when it not only has a soapy feel but can be scratched by a fingernail.