A geological boundary can be drawn more precisely than equipment can follow it. Material outside the preferred zone may enter the mining stream, changing the feed delivered to the plant. The owner must decide whether the mine plan represents that practical limitation credibly and whether processing assumptions use the resulting diluted feed rather than an idealised geological selection.
Define the movement being estimated
The study should explain what it calls dilution and where it is measured. Definitions and calculation boundaries can differ, making percentages difficult to compare without context. The technical team should identify the sources it expects: contact uncertainty, equipment selectivity or other conditions relevant to the proposed method. CIM's reserve guidance addresses dilution within mine planning. A financial reviewer should request the underlying mechanism and modelling method. A single allowance attached to every part of a deposit may hide important variation across mining shapes, operating conditions and different stages of the planned sequence.
Compare geology with practical mining units
A hypothetical narrow mineralised zone may sit inside a wider excavation shape that equipment and access require. The resulting feed must account for the material moved together. The owner should ask how proposed mining dimensions, drilling information and operating controls support the selection. Greater geological confidence can improve the model while leaving physical selectivity limits unchanged. Equipment choice and operating method therefore need evaluation alongside the resource interpretation. The relevant commercial comparison includes the cost of improved selectivity and its effect on recovery, throughput and schedule, rather than assuming precision is available without operational consequence.
Give the plant the same feed
The processing file should receive the quantities and characteristics implied by the mining plan. If the mine model adds material while the plant model keeps the undiluted grade and unchanged physical properties, the combined business case becomes inconsistent. Variability testing may need to investigate plausible blended material. JORC's framework treats mining and processing as connected modifying factors, supporting a review across the study boundary. The committee should be able to trace one representative period from the mining selection through feed calculations to product output without relying on incompatible assumptions held in separate spreadsheets.
Test the operating feedback loop
A development plan should describe how actual extraction and plant feed would be reconciled against the model. Differences need investigation before a planning allowance is revised. An owner can commission sensitivity work to understand whether the project depends on an unusually favourable selection outcome. Investors should assess the evidence for that outcome and the consequences if it proves harder to achieve. Dilution is commercially important because the plant treats physical material, including the material that arrives alongside the desired zone. A credible plan acknowledges that operating reality before presenting a forecast of saleable output or mining margins.
