• overburden
  • The material such as soil and rock lying above a mineral deposit that must be removed in order to work the deposit.
Abstract from DBPedia
    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. Overburden may also be used to restore an exhausted mining site during reclamation. Interburden is material that lies between two areas of economic interest, such as the material separating coal seams within strata.

    (Source: http://dbpedia.org/resource/Overburden)