Sampling Strategy and Grade Control for Recovery Improvement in Structurally Controlled, Narrow Vein-Hosted Gold Deposits: A Case Study from Unit 5 Gold Mine, Kwekwe Greenstone Belt, Zimbabwe

Small-scale gold operations hosted in structurally controlled, narrow quartz-carbonate vein systems commonly report disappointing recoveries and erratic grade outcomes despite reasonable metallurgical practice. This paper argues that the root cause in many such cases is not metallurgical but originates upstream, in the absence of a systematic, theory-based sampling and grade-control framework. Using Unit 5 gold mine in the Kwekwe Greenstone Belt of Zimbabwe as a case study — a four-shaft, structurally controlled vein system with narrow, pinch-and-swell vein width and characteristics typical of high-nugget-effect gold deposits — established sampling theory and the narrow-vein gold sampling literature are applied to design a face-sampling, quality assurance and quality control, and grade-reconciliation methodology fitted to the deposit's actual geometry. A phased turnaround action plan is presented, moving the operation from unsystematic mining decisions toward a defensible, code-aligned resource and grade-control base. The approach is transferable to comparable small-scale, structurally controlled vein gold operations elsewhere in the region.