St Barbara is also reimbursing $318,000 of drilling expenditure already incurred by Australian Potash.
St Barbara will now proceed to the second earn-in period, under which it will contribute $3.5 million to earn up to a 70 per cent interest in the Lake Wells Gold Project tenements.
Shares in St Barbara (ASX:SBM) are trading 0.9 per cent higher at $2.73.