In
mining,
overburden (also called
waste or
spoil) is the material that lies above an area that lends itself to economical exploitation, such as the rock, soil, and ecosystem that lies above a
coal seam or
ore body. Overburden is distinct from
tailings, the material that remains after economically valuable components have been extracted from the generally finely milled ore. Overburden is removed during
surface mining, but is typically not contaminated with toxic components and may be used to restore an exhausted mining site to a semblance of its appearance before mining began.