Busia's gold: recovery matters more than grade

The Busia and Busitema area sits within Archaean greenstone rocks continuous with the Kenyan and Tanzanian craton margin. Mineralisation is typically associated with quartz veining and sulphide zones, worked at surface by artisanal miners for a century.

A century of artisanal activity has left a useful, if informal, record: sites that remain economic to hand-work today are generally the higher-grade, more accessible portions of a vein system, while ground that was tried and abandoned by artisanal miners often signals either lower grade or a metallurgical difficulty that a modern plant would still need to solve.

Oxidised near-surface material is usually free-milling and recovers well through gravity and simple cyanidation. Below the oxide boundary, sulphide association raises the prospect of refractory ore requiring roasting or pressure oxidation, which changes the capital estimate by an order of magnitude.

Any project economics built entirely on oxide recovery assumptions carry an unpriced step change at depth. Ask for variability testwork across the transition, not composite averages.

This is not a theoretical risk in East Africa. Several regional projects on comparable greenstone geology have seen initial development plans built around encouraging oxide metallurgical results, only to encounter materially lower recoveries and a much larger capital bill once mining reached the sulphide zone. Investors reading a Busia-area technical report should specifically look for the depth at which the oxide-sulphide transition occurs and whether testwork actually crosses it.

Bottle roll and comminution data by domain, sulphide sulphur assays, and a stated position on where the oxide base sits. Reports that present a single recovery figure for the whole deposit are describing an ambition, not a flowsheet.

A developer could reasonably respond that early-stage technical reports are, by definition, based on the drilling and testwork available at the time, and that demanding full sulphide-domain variability testwork before a project has drilled deep enough to sample that material is asking for data that does not yet exist. Staged disclosure, oxide first, sulphide characterisation as depth is proven, is standard industry practice rather than a red flag on its own.

That is a fair process point, and we are not suggesting every early-stage Busia project is deliberately obscuring refractory risk. Our narrower argument is about how such disclosures should be read by outside investors: a recovery figure quoted without a stated domain and depth range should be treated as provisional rather than representative of full mine life, regardless of how confidently it is presented, and the absence of sulphide data at a given stage is information in itself.