An adit or stulm
is a horizontal or nearly horizontal passage to an underground mine.
Miners can use adits for access, drainage, ventilation, and extracting minerals at the lowest convenient level. Adits are also used to explore for mineral veins. Although most strongly associated with mining, the term adit is sometimes also used in the context of underground excavation for non-mining purposes; for example, to refer to smaller underground passageways excavated for underground metro systems, to provide pedestrian access to stations, and for access required during construction.
Gated entrance of an abandoned adit near Medford, Oregon, United States
Queen Louise adit, Zabrze, Poland
Horse adit in the abandoned lead mine, Nenthead, County Durham, UK
Two Brothers Adit, a small surviving mine entrance at the site of Eylesbarrow mine, Dartmoor, Devon
Underground hard-rock mining
Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands.
A 3D diagram of a modern underground mine with shaft access
Decline portal
Door for directing ventilation in an old lead mine. The ore hopper at the front is not part of the ventilation.