gobbing

from The Collaborative International Dictionary of English v.0.48
Gobbing \Gob"bing\, n. [See 1st {Gob}.] (Mining)
   (a) The refuse thrown back into the excavation after removing
       the coal. It is called also {gob stuff}. --Brande & C.
   (b) The process of packing with waste rock; stowing.
       [1913 Webster]
    

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