Geometallurgy in Gold Mining: Why Ore Variability Matters
A gold deposit is rarely uniform. Ore from one zone may be soft and free-milling, while material nearby may be harder, contain preg-robbing carbon or lock gold inside sulfide minerals. Geometallurgy connects geological characteristics with expected processing behavior so mine planners can anticipate how different ore types may affect throughput, recovery, reagent use and operating cost.
Evergreen investor education. This article does not describe GBDS geology, metallurgy, mineral resources, recoveries, production, costs or forecasts.
What a geometallurgical model does
Traditional resource models estimate variables such as grade, density and geological domain. A geometallurgical model adds processing-related attributes. Depending on the deposit and flowsheet, these may include ore hardness, mineralogy, oxidation state, gold deportment, recovery response, grind size, reagent consumption or the presence of penalty elements.
The goal is not to replace metallurgical testing with a single average. It is to map processing behavior spatially so the mine schedule and plant model can reflect the ore likely to arrive in each period. That can inform blending, stockpiling, plant design and the sequence in which ore zones are mined.
Why averages can hide risk
An average recovery may be reasonable for a life-of-mine summary yet still conceal difficult months or years. If a low-recovery domain arrives earlier than expected, ounces produced may fall even when tonnes and head grade meet plan. Harder ore may reduce mill throughput or raise grinding energy. Clay-rich material can create materials-handling issues, while changing mineralogy may alter cyanide, lime or flotation-reagent demand.
Technical disclosure standards recognize this importance. The Ontario Securities Commission’s Form 43-101F1 calls for discussion of relevant metallurgical testing, sample representativeness, recovery assumptions and known deleterious elements. Investors can look for whether test samples cover the deposit’s important grades, rock types, depths and weathering domains.
Current technical reports show the range
A March 26, 2026 SEC-filed technical report for the Kibali Gold Mine, current at December 31, 2025, reports different average recoveries across ore sources and weathering types. It also compares the geometallurgical model with plant performance. A separate SEC-filed San Gabriel project report describes gold geometallurgical units and recovery modelling. These reports concern unrelated properties and are cited only as examples of investor disclosure.
A hypothetical recovery example
Hypothetical example: assume one million tonnes of ore grading 1.5 grams of gold per tonne. That represents about 48,226 contained ounces before recovery. At 90% recovery, the simplified recovered total is about 43,403 ounces; at 80%, it is about 38,581 ounces—a difference of roughly 4,823 ounces. This linear example is not a forecast and excludes dilution, ore loss, ramp-up, inventory changes, payable terms and other operating factors.
Investor questions to ask
Investors can ask: How many variability samples support the model, and where were they collected? Are recovery and hardness assumptions assigned by domain or averaged across the deposit? Does the mine plan schedule materially different ore types? Can stockpiles and blending smooth those changes? Are plant capacity, reagent systems and tailings characteristics suitable for the full expected range? How often is the model reconciled against actual plant data?
A credible geometallurgical program does not eliminate uncertainty. It makes ore variability more visible and gives management tools to plan around it. For investors, the key is whether geological, metallurgical, mine-planning and financial assumptions tell a consistent story.
Educational disclaimer: This material is for general information only and is not investment, legal, tax, geological or engineering advice. Mining projects involve geological, metallurgical, operational, commodity-price, financing, environmental, regulatory and execution risks. Review current technical disclosures and consult qualified advisers before making investment decisions.