Talc By Lime Mineral & Chemicals

Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2. In loose form, it is the widely-used substance known as talcum powder. It occurs as foliated to fibrous masses, its monoclinic crystals being so rare as to be almost unknown. It has a perfect basal cleavage, and the folia are non-elastic, although slightly flexible. It is very soft and sectile (can be cut with a knife). Talc is not soluble in water, but it is slightly soluble in dilute mineral acids. Its colour ranges from white to grey or green and it has a distinctly greasy feel. Its streak is white.

Talc is used in many industries such as paper, plastic, paint, coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics etc.

Talc is widely used in the ceramics industry in both bodies and glazes. In low-fire artware bodies it imparts whiteness and increases thermal expansion to resist crazing. In stonewares, small percentages of talc are used to flux the body and therefore improve strength and vitrification. It is a source of MgO flux in high temperature glazes (to control melting temperature).