Largely demolished former potash mine site near Menteroda in the Unstruttal, where the three shafts of the Gewerkschaft Volkenroda reached extraordinary depths of approximately 1,000 metres.
The Gewerkschaft Volkenroda, operating as the Kaliwerk Volkenroda in Menteroda, was one of the most technically distinctive potash mines in Germany by virtue of its three shafts — the Schacht Volkenroda and two Pöthen shafts — all reaching depths of around 1,000 metres, making them the deepest in the German potash industry. Sinking of the founding Schacht Volkenroda (also known as Schacht Menteroda and later Carl-Eduard Schacht) began on 28 August 1906. The shaft was completed in 1909, reaching the potash seam at 977.5 metres and a final depth of 1,001 metres.
The mine also achieved the first and, as of the 1950s, only documented production of crude oil from a kali mine underground (from 1930), when the Erdöllagerstätte was discovered following several fatal explosions. Potash production continued through the DDR period until 1990–91. The mine operated as a going concern of the Kombinat Kali until 1999 in various capacities.
By the time photographic documentation was made in 1993 the headframe was still standing; by a later date virtually all above-ground structures had been demolished.
The origins of the Gewerkschaft Volkenroda lie in the Gewerkschaft Friedrichstein, founded in Gotha, which provided the corporate foundation for the subsequent development. The formal application by the Gewerkschaft Volkenroda for the first Betriebsplan was submitted to the Bergamt on 6 July 1906. The plan covered the initial buildings and plant and a provisional haulage installation. Still in 1906 a steam boiler was set up on the shaft site and sinking of Schacht Menteroda began on 28 August 1906 at a point 460 metres north of the Menteroda borehole. The first Obersteiger (head overman) was Albert Klaus from Gerbstädt, previously employed at the mine in Beienrode.
The concession field of the Gewerkschaft Volkenroda comprised 11 Prussian Normalfelder in the Herzogtum Gotha in the Gemarkungen Klein Keula, Menteroda, Obermehler, Volkenroda, Körner, and Hohenberge, adjoining the fields of Glückauf-Sondershausen, Pöthen, and Hüpstedt; and bordering also on Ludwigshall, Bleicherode, Felsenfest, and Sollstedt. The shaft was completed in 1909, having intersected the potash seam at 977.5 metres in excellent condition and quality. The final depth was 1,001 metres, and loading levels (Füllörter) were established at 648 metres. Because of the requirement under the 1910 Reichskaligesetz to demonstrate a multi-year reserve before commencing chamber extraction, the mine extracted exclusively from development headings for the first 8 to 10 years after reaching production.
The mine also owned the neighbouring Werk Pöthen outright (zusammen mit zwei fertig ausgebauten Schächten, Mühle und Hilfswerken ganz im Besitz von Volkenroda). Schacht Pöthen I reached 1,016 metres depth and Schacht Pöthen II reached 1,036 metres, while a third Pöthen shaft was begun in 1912 to 36 metres and then abandoned after the war. A standard-gauge connecting railway of 4 kilometres was constructed between Volkenroda and Pöthen. The mine's surface infrastructure included a salt mill, salt store, electric hoisting installation, materials magazine, locomotive shed, administration building, director's house, 61 staff and workers' dwellings with a masonry dormitory for 40 single men, 14 boilers of 100 square metres heating surface, and an electrical generating centre also supplying the Werk Pöthen. The double-shift winding arrangement used both an electric and a steam winding machine.
In 1917–18 combined Kaliabsatz of the Volkenroda and Pöthen operations was approximately 135,545–144,212 Doppelzentner K₂O, of which Volkenroda's own share was around 74,000–71,000 Doppelzentner annually. In 1919 combined sales were 115,144 Doppelzentner K₂O.
In 1923 a field exchange of 197,000 square metres was made with the Gewerkschaft Glückauf-West to regularise the boundary that prevented a straight through-drive to Schacht Pöthen I across a Gothaer Exklave. In 1924 a further 2,200,000 square metres were purchased from the same Gewerkschaft to round out the concession.
On 30 November 1930 the first oil strike in the Volkenroda underground workings occurred. In the course of 1930 several explosions with fatalities took place before the source was understood to be a petroleum reservoir. This became the only documented case of crude oil production from a kali mine in Germany. Petroleum extraction from underground continued at Volkenroda until 1991.
The mine operated through the DDR period as part of the Kombinat Kali, which was established in 1970. The Kombinat Kali entry records all three Volkenroda-Pöthen shafts as having depths exceeding 1,000 metres, with Schacht Pöthen I at 1,050 metres being the deepest shaft in the entire Kombinat. Potash production at Volkenroda was discontinued in 1990–91. The mine remained a going concern until 1999 in some capacity. A photograph taken on 18 September 1993 showed the headframe still standing over the Schacht Volkenroda (Carl-Eduard Schacht). A later photographic record notes that virtually all above-ground structures have since been demolished.