[1] The sites bear testimony to the intercontinental trade in mercury which generated important exchanges between Europe and America over the centuries.

The two sites represent the two largest mercury mines in the world and were operational until recent times.

Mercury played an important role in extracting gold and silver from ores, dug in American mines.

[5] Initially, the nomination was made together with Huancavelica mercury mine in Peru, in relation to the intercontinental route Camino Real.

The third, successful stage of the nomination focused on mercury mining in relation to technological and industrial processes that influenced the economical and cultural development of the two regions.