Sheeted vein gold deposits are often characterised by multiple sub-parallel veins and free-milling coarse gold. Inherent heterogeneity results in grade and process parameter variability, which increases project risk if not quantified. This contribution presents a case study that emphasises early-stage geometallurgical implementation to a high-grade deposit. It exemplifies how data can be acquired from a well-designed and planned programme to support resource estimation, a pre-feasibility study (PFS), trial mining and fast-track to production. During the pre-feasibility study, consideration was given to mining strategy with underground scenarios across: (1) a 400 000 t per annum bulk-mine operation based on longhole stoping; and (2) a high-grade selective small-scale operation based on shrinkage stoping. The PFS conclusion was that a selective operation was the best option allowing for acceptable project economics, a small footprint, fast ramp-up, less capital expenditure and aligned better with the expectations of local stakeholders. The selective mining scenario was based on a narrow high-grade zone within the centre of the sheeted vein system, comprising a 2-3 m wide zone. A tactical geometallurgical/ore control programme has been embedded into the operation. Overall, the geometallurgical programme has provided value to the project through focussing for the PFS to the narrow high-grade zone; resolving local grade; providing metallurgical recovery data for each block and allowing a blending strategy for sulphide-rich versus poor ore; and providing net acid generation prediction. Two and a half years of reconciliation data shows that the models are representing the orebody well. CITATION: Dominy, S C, OConnor, L, Glass, H J and Purevgerel, S, 2019. Geometallurgical application in an underground gold operation, in Proceedings Mining Geology 2019, pp 269278 (The Australasian Institute of Mining and Metallurgy: Melbourne).