What material is the basis for the lithography?

Lithography (from Ancient Greek meaning 'stone`) is a method of printing originally based on the immiscibility of oil and water. Lithography originally used an image drawn with oil, fat, or wax onto the surface of a smooth, level lithographic limestone plate. The stone was treated with a mixture of acid and gum arabic, etching the portions of the stone that were not protected by the grease-based image.