"Tailings" generally refers to the waste products from mills [except for dredge tailings which are the discarded coarse material from dredges]. "Dump" material is normally unmineralized "raw" rock from an open pit or underground mine. Further, mineralized rock and ore being stored for future processing on the surface is stored in "stockpiles".
Not asked, but perhaps interesting is the mining definition of "tunnel" which is an excavation that has both an entrance and exit [although there are some notable exceptions such as the Sutro Tunnel that drained some of the deep mines at Virginia City, Nevada]. "Adit" on the other hand is an excavation that goes into a hill or mountain - in other words almost all of the underground mines that do not have shaft access are, in fact "adits"
Sometimes mining terminology conflicts with the common use of the English language.
Ted Wilton
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