It has the same origins as china clay, but instead of being extracted from the rotten granite, it has been naturally transported by ancient rivers and deposited in its present position. During its journey, the particles of clay eroded, making them even smaller than they were already. This makes the clay exceptionally sticky and pliable. Well, it's hard to get a straight answer, but apparently its because it's carried from the pit in large blobs about the size of a beach ball. Ball clay is also used for the washbasin, the tiles and for some baths.
Many cosmetics have a geological origin.
One of the ingredients for soap, sodium hydroxide will have been processed from salt, maybe dug from Cheshire. Face packs are made from clay - some of the paler coloured ones are made form kaolin, but the really good muddy brown ones are a special kind of clay called Fuller's Earth. Fuller's Earth used to be used by fullers - people who cleaned sheep's wool before it was spun. It is an especially absorbent type of clay formed from very fine volcanic dust. Fullers Earth can still be bought from a chemists as a fine powder, just as it was used to dust through fleeces to absorb grease and dirt, and to lubricate the fibres to make them smooth and easier to spin.