In pit mining, the dirt and rock removed to reach the ore is usually called overburden. If it’s the waste rock dug out along with the ore, people may also call it spoil or waste rock.

Quick distinction

  • Overburden : the soil and rock above the ore body that has to be stripped away.
  • Waste rock / spoil : material excavated from the pit that is not valuable ore.
  • Tailings : the leftover material after the ore has been processed, not the dirt removed from the pit.

Plain-English version

If you’re asking about the stuff miners first peel off to get to the mineral, overburden is the best word. If you mean the extra rock they haul out and dump aside because it isn’t useful, waste rock is also common.

TL;DR

Overburden is the standard mining term for the dirt and rock taken out of a pit to expose the mineral below.