Open-pit mining
Open-pit mining extracts minerals from a large surface excavation by removing overburden and progressively deepening or widening the pit to reach ore.
Overburden: Soil and rock covering a mineral deposit that must be removed before extraction. Its removal exposes the ore that open-pit mining targets.
Porphyry copper deposit: A large, low-grade copper deposit associated with porphyritic igneous intrusions. Its broad, near-surface geometry commonly supports open-pit extraction.
Underground mining: Mineral extraction through shafts, tunnels, or other workings beneath the surface. It can reach deep deposits without removing the entire overlying land surface.
Acid mine drainage: Acidic, metal-rich water formed when sulfide minerals react with air and water. Exposed sulfide-bearing rock in pits and waste piles can generate acidic runoff.
Bingham Canyon Mine: A large copper mine in Utah, developed as an open pit in the Oquirrh Mountains. Its immense excavation illustrates the scale achievable in open-pit mining.
Bench (geology): A step-like horizontal level cut into the walls of an open excavation. Benches divide pit walls into workable and more stable sections.
Iron ore: Rock containing iron-bearing minerals in concentrations suitable for extraction. Many large iron ore bodies are mined from surface pits.
Strip mining: Surface mining that removes overburden in long strips to expose shallow, usually horizontal deposits. Its advancing strips suit layered deposits, unlike the expanding pit around a central ore body.
Mine reclamation: The process of restoring mined land toward a stable, usable condition. Reclamation addresses pit slopes, waste areas, and disturbed ecosystems after mining.
Chuquicamata: A major copper mine in northern Chile, historically known for its large open pit. Its development shows how a long-lived pit can expand through successive mining phases.