It has drilled 192 holes for 16,222m across the three primary targets, Grandao, Reservatorio and NOA, with the drilling at Grandao identifying a "significant extension to the known mineralised pegmatites supporting the excellent potential for further increases in the existing 14 million tonnes at 1.1% Li₂O mineral resource estimate", it said.

Highlights from Grandao drilling included 25.15m at 1.38% Li2O from 96.85m, 41.35m at 1.30% Li2O from 103m, 14.4m at 1.57% Li2O from 148.60m, 47m at 1.35% Li2O from 66m, and 30m at 1.33% Li2O from 45m.

Savannah has now mobilised a second diamond drill rig on site to support its ongoing  feasibility study, while the third phase of the metallurgical test work programme is also said to be progressing well.

The company has already upped Mina do Barroso's resource estimate twice.

CEO David Archer said Savannah's confidence in the potential to increase the project's resource estimate had increased as the zones in the main Grandao deposit thickened and drilling extended the deposit down dip.

"Mina do Barroso has developed at an exceptionally fast pace since the first hole was drilled on July 24, 2017. We have gone from a point of having no mineral resource estimate to having made one of Europe's most significant mineral discoveries of a mineral that is of vital and strategic importance to European industry," he said.

The market was not that impressed with Savannah's results, with shares down 1.6% Thursday to 9.15p (US12c).