The phrase "salt mines" refers to a place where salt is extracted from the ground. It can also be used figuratively to describe any difficult or tedious work that feels repetitive or like hard labor. Full definition
The mineral content in salt mined from many parts of the world provide our bodies with trace minerals that we otherwise would not get. (powerfullymade.com)
You will meet the villagers who explain ancient salt mining techniques and have a chance to participate. (costsavertour.com)
Himalayan salt is a type of rock salt mined from ancient salt beds in the Himalayan mountains. (wellnessmama.com)