Stripping ratio

In surface mining, stripping ratio or strip ratio refers to the amount of waste (or overburden) that must be removed to release a given ore quantity. It is a number or ratio that express how much waste is mined per unit of ore. The units of a stripping ratio can vary between mine types. For example, in coal mining the stripping ratio is commonly referred to as volume/weight., whereas in metal mining, stripping ratio is unitless and is expressed as weight/weight. A stripping ratio can be expressed as a ratio or as a number.