This salt is directly from the ancient Roman salt mines at Rio Maior not far from Vinhos Cortém.

The first products we have selected for you are both made very near Cortém and are uniquely Portuguese.
The Salinas of Rio Maior has been working since 1170 when it was owned and run by Templar Knights. It is a wonderful salt from brine which flows naturally into an ancient well. and is then pumped to the pans for evaporation. There are many salt products to choose from.

Salinas. (Salt pans)
http://salinasderiomaior.pt/
http://lojadosal.blogspot.pt/