The mining method best suited for a disseminated ore body in weak, fractured rock is:

• A. Open pit with benching
• B. Block caving
• C. Sublevel stoping
• D. Placer mining

Answer: (B)

When ore is disseminated through weak, fractured rock, you want a method that uses the rock’s tendency to collapse rather than trying to hand-hold stable openings in fragile material. Block caving fits this scenario because it lets a controlled undercut start a progressive collapse of the overlying rock, creating large draw points at the bottom where ore and broken material flow to the surface. This approach is economical for very large, low-grade ore bodies and deep deposits, where the rock mass is not strong enough to support traditional underground stoping or large-scale open-pit walls. The broken rock produced by the cave is part of the extraction process, so you don’t rely on narrow, stable excavations through weak rock.

Open pit with benching can be used in some cases, but in weak, highly fractured rock slope stability becomes the dominant constraint, making large, stable pit walls costly or impractical for deep, disseminated ore. Sublevel stoping requires a relatively competent rock mass and clearly defined ore zones; in this kind of fractured rock it can be unstable and more expensive due to the need for extensive support and handling of unpredictable breakage. Placer mining is for alluvial or loose surface deposits, not for ore embedded in fractured rock.