The stock jumped as much as 46% on the news, with Riversgold of the belief "there is great potential for the Earl Grey and Bounty systems to continue into the … tenement" subject of the option.
Riversgold is initially paying A$150,000 in cash and issuing the vendor Cacique Resources four million shares, with a further payment of $700,000 required to exercise the option for an 80% stake in the lithium rights.
The vendor would hold a 20% free-carried interest if the option is exercised.
Riversgold has other lithium ground in the region and in the Pilbara.
The junior had $2.8 million cash at the end of June.
Shares in Riversgold were up 31% in afternoon trade, capitalising the company at $35.5 million.