Talc Talc Talc or talcum is a clay mineral composed of hydrated magnesium silicate with the chemical formula HMg(SiO) or MgSiO(OH). In loose form, it is (in ratio with or without corn starch) one of the most widely used substances known as baby powder. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage, and the folia are not elastic, although slightly flexible. The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 1 as the hardness of talc. Talc can easily be scratched by a fingernail. Talc
Friedrich Mohs Friedrich Mohs Carl Friedrich Christian Mohs (; 29 January 1773 – 29 September 1839) was a German geologist and mineralogist. He was the creator of the Mohs scale of mineral hardness. Mohs was born in Gernrode, Germany. Mohs studied chemistry, mathematics and physics at the University of Halle and also studied at the Mining Academy in Freiberg, Saxony. After assuming the position of a foreman at a mine in 1801, Mohs moved in 1802 to Austria, where he was employed in trying to identify the minerals in a private collection of a banker. In 1812 he moved to Graz where