A crayon is a stick of colore wax, charcoal, chalk, or other materials used for writing and drawing. A crayon made of oiled chalk is called an oil pastel; when made of pigment with a dry binder, it is simply a pastel. A grease pencil or china marker (UK chinagraph pencil) is made of colored hardened grease and is useful for marking on hard, glossy surfaces such as porcelain or glass.