Former hard coal shaft site in Hohndorf near Oelsnitz, part of the Steinkohlen-AG Bockwa-Hohndorf-Vereinigtfeld from 1872, whose Schacht I was deepened to 1,200 metres in 1942 as the Rudolf-Breitscheid-Schacht — briefly the deepest coal shaft in Europe —
Schacht Vereinigtfeld 3 (also identified as Breitscheid-Schacht III in post-war sources) was one of three shafts of the Steinkohlen-Aktiengesellschaft Bockwa-Hohndorf-Vereinigtfeld at Hohndorf in the Lugau-Oelsnitzer Steinkohlenrevier. The company was founded in February 1872 and sinking of its first shaft began in May 1872, reaching 835 metres by 1877. The three Vereinigtfeld shafts served a combined Grube under the Betriebsabteilung Vereinigtfeld within the Gewerkschaft Gottes Segen after 1920.
Following rationalisation, all three shafts were progressively closed or mothballed by 1931. The main Vereinigtfeld Schacht I was subsequently reopened under DDR administration, deepened to 1,200 metres and renamed Rudolf-Breitscheid-Schacht; at that depth it was the deepest coal shaft in Europe. Together with the companion Breitscheid-Schacht II it was filled in 1973.
The Schacht III site was not reopened and its Halde is the subject of ongoing Altbergbau-Sanierung works by the state of Saxony.
The Steinkohlen-Aktiengesellschaft Bockwa-Hohndorf-Vereinigtfeld was constituted in February 1872 near Lichtenstein. In May 1872 sinking of Schacht I began; by 1877 it had reached 835 metres depth. Schacht II was angeteuft alongside it in the same early period; Schacht III followed as a Wetterschacht or auxiliary shaft. All three Vereinigtfeld shafts lay in the Hohndorf Ortsflur, connected to the regional Zechenbahn network. By around 1900 the schächte served an active underground field within the larger Lugau-Oelsnitzer Steinkohlenrevier. Around 1895 the Sächsisches Oberbergamt estimated that coal seams in the combined Hohndorf-Vereinigtfeld field had a Teufe range from 700 to over 1,000 metres.
Following the economic disruption of the First World War, the Steinkohlen-AG Bockwa-Hohndorf-Vereinigtfeld and other distressed enterprises in the revier were merged in 1920 into the newly created state-owned Gewerkschaft Gottes Segen, which grouped the Betriebsabteilungen Lugau, Oelsnitz, Kaisergrube, and Vereinigtfeld. Rationalisation followed rapidly. In the Betriebsabteilung Vereinigtfeld, production was concentrated on Schacht I and the Vereinigtfeld II and III Schächte were closed. By 1931 the Vereinigtfeld operations as a whole were placed in Stilllegung. The shaft at the Schacht III location was among those closed during or shortly after the 1920s rationalisation.
Under DDR administration following the end of the Second World War and the Volksentscheid in Sachsen of 30 June 1946, the already-filled former Vereinigtfeld Schacht I was again aufgewältigt and then weitergeteuft from 835 metres to 1,200 metres between 1938 and 1942 — a process that began before the DDR era under wartime pressure for coal production and was continued after 1945 — making it at that depth the deepest coal shaft in Europe at the time. This reopened shaft was designated the Rudolf-Breitscheid-Schacht, named after the SPD politician Rudolf Breitscheid (1875–1944). The companion shaft at the same Breitscheid-Schacht complex was designated Schacht II. Both were used for coal extraction from the deeper reserves until production was ended. Together the two shafts were verfüllt in 1973.
The coordinate for Vereinigtfeld 3 corresponds to the Schacht III site of the original Vereinigtfeld AG, which is one of the three Breitscheid-Schächte now documented by the Sächsisches Oberbergamt in connection with Altbergbau-Sanierung (Haldensicherung) requirements. The Halden associated with the Breitscheid-Schächte I, II, and III in Hohndorf are partly bewaldet and affected by Erosionserscheinungen and Standsicherheitsprobleme. They are owned by the Gemeinde Hohndorf. Sanierungsprojekte for the Halden were in preparation under EFRE Sachsen 2014–2020 funding.