A scoping study for Stonewall Resources Ltd.'s Theta Hill gold mine in South Africa pegged an after-tax net present value of US$152 million, discounted at 7.5%, with a 132% internal rate of return and payback period of about 7.4 months.

Capital costs are estimated at US$16 million, with a 10-month construction period. The first ore is expected in 12 months.

The open-cut gold mine will have the potential to produce an average of 67,000 ounces of gold per year over a mine life of 7.6 years.

The study delivered all-in sustaining costs of US$569 per ounce, including royalties.

Theta Hill hosts an open-cut resource of 4.48 million tonnes at 4.14 g/t for 600,000 ounces in the indicated and inferred categories. The JORC 2012-compliant resource is estimated at 39.15 million tonnes at 4.57 g/t gold for 5.75 million ounces.

The company is focused on converting part of its large resource into a reserve, while drilling is underway to improve the confidence category to primarily indicated ahead of the reserve declaration scheduled for the first quarter of 2019.

Stonewall said Oct. 15 that its board is committed to progressing the project toward a decision to mine in 2019.