De Grey Mining (ASX:DEG) said a conceptual study at its Hemi project in Western Australia showed that there may be potential for underground mining beneath the existing mineral resource estimate, according to a Thursday filing with the Australian bourse.

The study, based on the mineral resource estimate in November 2023, focused on the possibility of underground mining in areas beneath the Diucon and Eagle definitive feasibility study open pit designs, part of the larger Hemi project, the filing said.

The results indicate that the project could support substantial additional resources, with mine plan stopes estimated to contain about 355,000 ounces of gold beneath the Diucon open pit and 460,000 ounces beneath the Eagle definitive feasibility study open pit.

The conceptual study also suggests that the Hemi mineral resource estimate could potentially extend to depths beneath all the Hemi definitive feasibility study open pit designs, offering an additional 3.2 million ounces of gold, the filing added.

The study highlights a potential maximum haulage rate of 4 million to 5 million tonnes per annum, the company said.

De Grey Mining will continue its wide-spaced step-out drilling at Hemi to extend mineralization and complete infill drilling at the Eagle deposit to refine its underground mine plans.

Shares of the company fell nearly 3% at market close Thursday.

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