According to the Mohs hardness scale, which is used to classify the hardness of minerals, talc is the softest mineral with a hardness number of 1. It is a silicate mineral that contains magnesium and water arranged into sheets in its crystal structure. Talc is easily scratched by the fingernail and is sectile, which means it can be easily cut or carved. It is used in a variety of products, including talcum powder and rubber lubricant.