Savannah has been carrying out reverse circulation drilling at the Aldeia Block A, approximately two kilometres south-east of the Grandao deposit at the mine.
Finds include 45 metres at 1.7% lithium oxide, including 22 metres in the same hole at 2.0%. Others include 32 metres at 1.5% lithium oxide and another 32 metres in the same hole at 1.1% lithium.
At Grandao itself, drilling has found 12 metres at 1.1% lithium oxide and six metres at 1.7% lithium oxide.
The 2.0% grade discovery is the highest Savannah has ever made at Mina do Barroso, it said.
Savannah is continuing to drill at Aldeia Block A, tracing the pegmatite body further down dip and along strike to the west. Savannah expects results to increase its current 23 million tonnes of ore resource at the mine.
Chief Executive David Archer said: "These latest results from Aldeia and Grandao include the highest-grade ever reported at Mina do Barroso of 22 metres at 2% lithium oxide, demonstrating the full scope of Mina do Barroso's exciting potential is still being realised.
"High-grade mineralisation has been identified along strike and at depth, indicating the potential to further expand the existing resource and significantly increase the potential life of mine."
"Results from recent workflow have continued to solidify Mina do Barroso's status as western Europe's most significant new spodumene lithium discovery positioning Savannah as a key strategic player in Europe's upstream lithium value chain," Archer added.
Savannah shares were 2.4% higher on Wednesday at midday at 5.58 pence each.