(Talc) is a layered silicate which is a hydrate.
Theory of MgO style chemical formula 3, 4 - SiO2, H2O, and the theory of chemical composition as follows: 31.68% MgO style SiO2 H2O 63.47% to 4.75%, the natural quality of pure talc ore are very few, most associated with other mineral impurities, common associated minerals include chlorite, serpentine, magnesite, tremolite, dolomite, etc.
Talc is often white, light green, microstrip pink, light grey, with impurities the more the color is deeper, even dark grey, black.
Monoclinic crystal system, ore presents flaky, fibrous and dense.
Pearly luster or oily luster, the heating effect of the talc are substantially heated, lose adsorbed water during 120 ~ 200 ℃, 600 ℃ when begin to lose part of the structure of water, until 1050 when the structure all the water out.
The best way to identify talc is to conduct X-ray diffraction analysis or thermal analysis.