Under Spanish domination it was decided to subordinate the mining activities to the grant of concessions from the State administration. At least forty concessions for exploration and exploitation of Sardinian ore bodies were assigned. Eight of them were general concessions, extended to the whole territory of the island and eighteen were limited to the circle of Iglesias. The assigners of the territory of the island had to pay to the Treasury 10% of the value of the extracted mineral. The first attempt to enhance the activity of the silver vein of Sarrabus, that had been relinquished for more than one thousand years, dates back to this period. In fact, on 6 June 1622 a certain Gio. Antonio Agus was granted a permit of prospecting around Monte Narba, near the town of San Vito.