IGO is paying 23c per share for nine million VMC shares, with the stock closing Friday at 18c.
VMC had $4.4 million cash at the start of the June quarter.
Meanwhile, IGO can progressively earn up to 70% by spending $6 million on VMC's Bridgetown-Greenbushes tenure.
In addition, if it completes a prefeasibility study the miner has the right to acquire the balance at "fair market value".
VMC's portfolio also includes a 30% interest in the emerging Youanmi gold play being worked-up by Rox Resources.
Shares in VMC were up 10% to 20c in morning trade, capitalising the company at about $30 million.