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
Åkermanite Åkermanite Åkermanite (CaMg[SiO]) is a melilite mineral of the sorosilicate group, containing calcium, magnesium, silicon, and oxygen. It is a product of contact metamorphism of siliceous limestones and dolostones, and rocks of sanidinite facies. Sanidinite facies represent the highest conditions of temperature of contact metamorphism and are characterized by the absence of hydrous minerals. It has a density of 2.944 g/cm. Åkermanite ranks a 5 or 6 on the Mohs scale of mineral hardness, and can be found gray, green, brown, or colorless. It has a white streak and a vitreous or resinous luster. It has a tetragonal crystal system