The archive defines open-pit stone mining by the removal of surface cover and weathered rock before a face is developed. It then separates the method into hillside, sunken and pit forms.
Hillside open pit
The orebody lies at an angle to horizontal ground, so the working face is built on the slope. Access, benches and transport follow the hillside rather than descending inside a level surface exposure.
Sunken open pit
The orebody is described as broadly horizontal with a large area exposed at the surface. Mining proceeds downward from that surface, layer by layer, producing a working area below the original ground level.
Pit mining
The source treats a pit as a special and deeper stage of sunken open-pit mining. A hillside operation can evolve into a sunken form and later into a well-like pit as extraction continues.
It says many pits around the world are deeper than 50 m and that some reach 80 m or more. No mines or measurement dates are identified for that observation.
What the three labels describe
These categories describe the relationship between orebody, terrain and direction of advance. They do not by themselves define slope stability, bench geometry, drainage, haulage or the cutting method. Those decisions need the actual deposit and mine design.
