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
Bityite immersion method are "α = 1.650", "β = 1.658", "γ = 1.660" with 2V calculation of 52.9°. Bityite’s specific gravity is 3.14, and it has a hardness of 4−4.5 based on Mohs scale of hardness. Bityite’s luster is vitreous and pearly on cleavages, and it has a perfect micaceous cleavage on the {001} miller index. Bityite’s crystal habit can display thin and pseudohexagonal platy crystals. Bityite Bityite is considered a rare mineral, and it is an endmember to the margarite mica sub-group found within the phyllosilicate group. The mineral was first described by Antoine François Alfred Lacroix in 1908, and