The move has sparked investor concerns about the future supply of lithium.
As per the LoI, ExGen has paid $500,000 (C$688,977) as consideration for the silver stream.
The phase one programme included 11 diamond drill-holes totalling 906m.
Output is forecast to increase strongly with an annual growth rate of 6% to reach 3,404.1kt as operations normalise.
Geoscience Australia's Karol Czarnota considers Australia's critical mineral potential and how government investment is shaping international supplies.
