In mining and in archaeology, overburden (also called waste or spoil) is the material that lies above an area of economic or scientific interest. In mining, it is most commonly 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. Overburden may also be used as a term to describe all soil and ancillary material above the bedrock horizon in a given area. In bonsai the word is also used of the soil over the top of the roots of a tree collected from the wild. It can denote decades of fallen needles, leaves, and other materials that fall over the top of a tree's roots in the wild.
In particle physics, the overburden of an underground laboratory is important because it indicates how shielded the facility is from cosmic radiation.
A related term is interburden, meaning material that lies between two areas of economic interest, such as the material separating coal seams within strata.
By analogy, overburden is also used to describe the soil and other material that lies above a specific geologic feature, such as a buried astrobleme.