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
Universalmuseum Joanneum collection traces its origin to the private collection of Archduke Johann, which encompassed several thousand pieces at that time. Today the inventory has grown to about 80,000 specimens. The collection presents minerals from across the world as well as a Styrian regional collection. The mineralogy department of the Joanneum was where Friedrich Mohs developed the Mohs scale of mineral hardness which remains authoritative. He was the first curator of the Joanneum. Schloss Eggenberg was added to the registry of the Graz Old Town as a UNESCO World Heritage Site in 2010. Schloss Eggenberg is the most significant palace ensemble in