Talc is a clay mineral magnesium with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch. This mineral is used as a thickening agent and lubricant; is an ingredient in ceramics, paint, and roofing material; and is a main ingredient in many cosmetics. to fibrous form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form.
The Mohs scale of mineral hardness is based on scratch , ranging from 1 to 10, a value of 10 being the hardest of minerals. The hardness of talc, the softest of minerals, defines the value of 1 on the scale. (Any mineral with a value less than 2 can be scratched by a fingernail, talc produces a white streak; though this indicator is of little importance, because most silicate minerals produce a white streak. Talc is translucent to opaque, with colors ranging from whitish grey to green with a vitreous and pearly luster. Talc is not soluble in water, and is slightly soluble in dilute mineral acids
Soapstone composed predominantly of talc.