Savannah found the three pegmatites over a strike of more than 250m and a depth of over 100m through reverse circulation (RC) drilling.
The main intersections at the deposit were 23m at 1.14% Li₂O from 9m; 14m at 1.21% Li₂O from 18m; 90m at 1.23% Li₂O from 39m, including 34m at 1.6% Li₂O from 94m; 69m at 1.29% Li₂O from 20m, including 24m at 1.58% Li₂O from 48m; and 35m at 1.19% Li₂O from 16m, including 21mm at 1.45% Li₂O from 19m.
Savannah said the results highlighted the potential to increase the current mineral resource estimate of over 20 million tonnes with 20,000 tonnes contained Li₂O.
"This new discovery is likely to positively impact the current feasibility study and further work at Pinheiro will now be fast tracked so that it can be included," the company said.
Meanwhile, Savannah also carried out infill RC drilling at the Reservatorio and NOA deposits, which it said confirmed the continuity and grade of the mineral resource estimate, as well as expanded both deposits by confirming mineralisation over strike lengths of 500m and 400m, respectively.
Results from the drilling at Reservatorio included 23m at 1.29% Li₂O from 24m; 27m at 1.03% Li₂O from 24m; 24m at 1.00% Li₂O from 26m; 42m at 1.21% Li₂O from 51m; and 27m at 1.08% Li₂O from 58m.
At NOA, it intersected 19m at 0.97% Li₂O from 99m; and 21m at 0.92% Li₂O from 57m.
Savannah said further drilling was planned at both deposits, as they both remained opened.
Diamond drilling was also ongoing at the project's Grandao deposit.
Looking at Mina do Barroso as a whole, 275 holes have been drilled so far for 23,072m and the company expects to complete the third phase of metallurgical test work in the December quarter.
Savannah CEO David Archer said the drilling had outlined the fourth major deposit at Mina do Barroso and highlighted "the still unconstrained nature of the resource potential of the overall lease area".
"Having already increased our mineral resource estimate by over 500% in a little over a year we are excited by the discovery of three new pegmatites at the Pinherio deposit, which could further enhance the scheduling flexibility of a mine development and add to the overall mine life," he said.
Savannah's shares were up 4.2% Wednesday at 6.2p (US8.16c).