Former hard coal mine in Großrosseln, sunk 1958 as the youngest colliery in the Saarland, with its 1960/61 concrete Förderturm at the Warndtschacht surviving alongside the listed 1915 Fachwerk headframe over Schacht Gustav II from the earlier Grube Velsen
The Grube Warndt at Großrosseln was the youngest Bergwerk in the Saarland, formed in 1958 when the Saarvertrag of 1956 allowed the development of the Warndtkohlengebiet under German administration. Planning for a major coal operation in the Warndt had begun as early as 1938 but was prevented by the Second World War. Construction of the new Grube began on 14 March 1958; the Warndtschacht, at 1,160 metres the deepest shaft in the mine, was also sunk that year.
The concrete Förderturm over the Warndtschacht was built in 1960/61 by the Mannheimer Niederlassung of Philipp Holzmann AG and equipped with a 70-metre winding tower. The mine began production in 1963, extracting Fettkohle from the Sulzbacher Schichten. It also incorporated the former Grube Velsen Schächte in 1964, including Schacht Gustav II whose 1915 Fachwerk-Strebengerüst is a listed monument at Großrosseln.
The Grube Warndt was merged in 1988 with the Grube Luisenthal to form the Verbundbergwerk West; in 2004 the combined entity became the Bergwerk Saar, which closed in June 2012.
The Warndtkohlengebiet, the coal-bearing forests of the Warndt near Großrosseln on the French border, had been prospected since the nineteenth century and mining plans had been formed as early as 1938, when a Großschachtanlage was intended. The Second World War prevented development. Under the postwar French administration, Houillères du Bassin de Lorraine (HBL) sank the Schacht St. Charles IV in 1948–1953 on Großrosselner Gemarkung as an extension of the French Lorraine basin operations. The Saarvertrag of 1956 returned the Warndtkohlenfelder, previously leased to France, to German administration and authorised the construction of a German mine.
Construction of the new Grube Warndt began on 14 March 1958. The Warndtschacht was sunk in 1958 as the Hauptförderschacht; it served also as the Seilfahrt- and Materialschacht. Its final depth was 1,160 metres below NN. The Beton-Turmförderanlage — a concrete Förderturm described by contemporaries as the modernste Zechenanlage Westeuropas and standing 70 metres high — was designed to handle the demands of deep coal winding. It was erected in 1960/61 by the Mannheimer Niederlassung of Philipp Holzmann AG. Production began in 1963, extracting Fettkohle from the Sulzbacher Schichten, primarily intended as Kokskohle for the saarländische Stahlindustrie. The mine had abbauwürdige Vorräte of approximately 190 million tonnes to a depth of −1,100 m NN, with Flözmächtigkeiten ranging from one to six metres.
The Warndtstollen was driven from 1963 to 1965 at 13 m² cross-section over a length of 2,100 metres. In 1964 a Verbundstrecke from Warndt to the former Schacht St. Charles IV was angefahren. In 1964 the Schächte of the formerly independent Grube Velsen at Großrosseln were incorporated as Außenschächte; these included Schacht Gustav II, whose 1915 Fachwerk-Strebengerüst is the oldest surviving headframe at the site and is listed on the Denkmalliste together with the associated Fördermaschinenhaus, Waschkauen, Zechenhaus, and Verwaltungsgebäude. The Grube Velsen ensemble is described as the only near-completely preserved Tagesanlage from the era of the Preußischer Bergfiskus in the Saarland. The Schacht Lauterbach (931 metres deep) served as an ausziehender Wetterschacht; its 1979 Abteufgerüst still stands. The Schacht St. Charles, previously sunk by HBL, served as a Wetter- and Seilfahrtschacht from 1962. In 1981 a further underground Stollen 2,550 metres long connected the Grube Warndt to Schacht Ludweiler of the former Grube Velsen.
In 1988 the Gruben Warndt and Luisenthal consolidated into the Verbundbergwerk West. The Durchschlag between Warndt and Luisenthal underground was completed in 1994 over a 3,200-metre Strecke. On 1 January 2004 the Verbundbergwerk West became part of the Bergwerk Saar, the last colliery in the Saarland. The Bergwerk Saar ceased coal production in June 2012. The Warndtschacht surface complex at the main site — with its concrete Förderturm of 1960/61 — and the separate Schacht Gustav II ensemble at the listed Grube Velsen site are the principal surviving surface elements of the Grube Warndt's history.