Deads are the unmineralized or low-grade rock masses immediately adjacent to or enclosing a profitable ore vein. Miners must often blast and move this barren material to access the valuable minerals, treating it as waste that ends up on the spoil heap or is used as backfill.
We had to muck out three tons of deads just to expose the hanging wall of the main vein.
The term is an older mining expression, reflecting the idea that the rock is 'dead' of any valuable metal.
Also heard as
- country rock
- waste rock
- gangue
Related terms
Country rock
The pre-existing, non-mineralized rock that surrounds and encloses an orebody or igneous intrusion.
Gangue
The commercially worthless rock or mineral matter mixed with valuable ore.
Tailings
The waste material left over after the valuable minerals have been extracted from ore.
Mullock
Waste rock or barren ground excavated during the search for an ore body.