The Rosemont deposit is part of Regis' greater Duketon gold project in Western Australia's Eastern Goldfields.
Rosemont has an open pit that started operating in 2013, and a standalone crushing and grinding plant that pipes ore slurry to the Garden Well carbon-in-leach facility.
The life of mine at Rosemont is expected to extend to 2024.
With a combined open pit and underground mine Regis is expecting to unearth 10.3 million tonnes of ore at 1.72 grams per tonne, for 570,000 ounces.
Of this, 62%, or 356,000oz, will come from the open pit, while 38% - 214,000oz - will be from underground.
Development work will begin this quarter, including permitting, long lead capital item ordering and underground mining contract tendering, while portal develop...