How can extraction costs change the amount of ore in a mineral deposit?

The amount of material classified as ore in a mineral deposit is directly influenced by extraction costs because these costs determine the break-even grade—the minimum concentration of a valuable mineral required for mining and mineral processing to be profitable.1

Material with a grade higher than the break-even point is considered ore, while material below it is classified as waste. Consequently, the total volume of exploitable ore reserves fluctuates based on economic factors:1

• Cost Increases: If extraction costs rise—for example, by transitioning from open-pit to more expensive underground mining—the break-even grade increases. This renders lower-grade portions of the deposit unprofitable, effectively reducing the total amount of ore.1
• Cost Decreases: Conversely, if extraction costs are lowered through improved efficiency or technology, the break-even grade drops, allowing previously uneconomical, lower-grade material to be reclassified as profitable ore.1

Ultimately, determining what constitutes ore is a dynamic economic assessment rather than a fixed geological fact, as it depends on the balance between expected commodity prices and the costs of recovery.12