Werra-Kalibergbau-Museum Heringen

Useful Information

Location:	Hauptstraße 15, 36266 Heringen (Werra). (50.886852, 10.006635)
Open:	temporarily closed. [2025]
Fee:	temporarily closed. [2025]
Classification:	Salt Mine
Light:	Incandescent
Dimension:
Guided tours:	self guided
Photography:	allowed
Accessibility:	no
Bibliography:	Hermann-Josef Hohmann, Dagmar Mehnert (2004): Bunte Salze, weisse Berge, Ulmenstein, pp 192, ISBN-10: 3980973808, ISBN-13: 978-3980973809. pdf
Address:	Werra-Kalibergbau-Museum, Hauptstraße 15, 36266 Heringen (Werra), Tel: +49-6624-54-212-0. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

1893	Potash salt is discovered during drilling.
1895	First shafts are sunk.
1900	Potash from Werra and Ulster on the market for the first time.
1938	Most serious mining accident with 11 fatalities caused by carbon dioxide.
1991	Last remaining cable car is decommissioned and dismantled.
1994	Werra-Kalibergbau-Museum opened to the public.
1996	Beginning of the guided tours on Monte Kali.
01-OCT-2022	Museum closed for renovation.
2027	Scheduled reopening.

Geology

The potash seams of the Werra sequence originate from the Zechstein 1, from the Permian. This period of a huge arid basin, into which seawater repeatedly penetrated and evaporated, led to the formation of massive evaporite deposits. The series of deposits goes from lime to gypsum to various salts, the separation of the individual deposits is due to their different solubility. As potassium salts are deposited very late, there are incomplete series, simply because fresh seawater penetrated beforehand. However, it is also possible for the fresh water to redissolve the salts. In the Werra sequence, three rock salt deposits were deposited, but only two potash deposits.

After the deposition of the evaporites had ended, water-blocking clay layers such as the Braunrote Salzton and the lower Letten, also known as Staßfurt-Ton, were deposited on top. Their water-blocking properties prevented the salts from being reached by the groundwater. Above this is the plate dolomite, which is 5 to 40 m thick and carries a lot of groundwater. This led to considerable technical problems in the early years. And this groundwater is also highly saline, which causes further problems.

A special feature of this region is the comparatively frequent carbon dioxide inclusions in the salt. If these are cut during mining, explosive carbon dioxide eruptions can occur. It is assumed that the carbon dioxide is of volcanic origin.

Description

Werra-Kalibergbau-Museum Heringen (Werra Potash Mining Museum in Heringen) offers an exhibition on the mining of potash, its use in agriculture, the environmental impact of potash mining and its significance for the people of the Werra Valley. As the museum is currently undergoing a complete overhaul, we will only give a relatively rough description of the topics covered here; a more detailed description can only be provided once the museum has reopened. The Werra Valley was a very rural area at the end of the 19th century; the industrial revolution had bypassed the area due to the poor soil and lack of natural resources. Many younger people migrated to the industrial centres or overseas in search of work. But the fact that there were no mineral resources here changed in 1893 with the first potash discovery south of the Harz. Previously, only rock salt had been drilled, but its extraction was less interesting. However, before the invention of artificial fertilisers, potash salt was an important fertiliser, which is why the mining of potash was extremely profitable. In 1893, the discovery of potash salts was reported in the newspaper, whereupon Kalifieber (potash fever) broke out. Shafts were sunk from 1895, but the plate dolomite above the salt deposit was karstified, leading to water ingress. The cost of dewatering exceeded the plans, and it took much longer than planned. Nonetheless, the deposits were finally reached.

An important company during this time was the Gewerkschaft Wintershall (Wintershall trade union). The German word Gewerkschaft is today mostly used for labour union, in this case it is a miner’s term for ‘trade union’ and refers to a collection of Gewerke, i.e. mining licences. And Winterhall is derived from the drilling contractor Julius Winter. This company played a key role in this area. The engineer August Rosterg took over the management in 1898 and developed the mine into a highly profitable company. He constructed a special dewatering system, the Tomson’sche Wasserzieheinrichtung (Tomson dewatering system), which considerably reduced costs and time. From 1900 onwards, potash was mined, which was extracted by hand and transported to Salzungen railway station by horse and cart. Now, however, the exodus was reversed, personell of all kinds was needed, and people moved to the area to work here. Due to a lack of miners in the area, they are recruited from outside. They not only brought their mining skills with them, but also their traditions and customs and their sense of mining status. They set up the first Knappenvereine (miners’ associations) as early as 1902, and the pace of development accelerated. Electrification, processing of the potash salt, improvement of the railway connection, an entire industry was built up. From 1908, the potash salt was processed in chemical factories. The founding period ended in 1914 with the outbreak of the First World War. The expansion of the mines came to a standstill, the miners were at the front, as potash mining is not important for the war effort there is a lack of material and, of course, explosives.

The German potash industry had a quasi world monopoly on potash for almost 60 years. This was simply because the only known deposits were in Germany. However, this ended because Alsace and the potash mines there now belonged to France. Whether this really had as great an impact as this statement suggests is questionable, however. Even before that, not only the individual mining districts but even the individual mines were competitors. The potash district was split in two at the end of the Second World War, with one part located in Hesse and the other in Thuringia and therefore in the GDR. However, there are legends that the mines were connected underground. After reunification, the East German mines were administered by the Treuhand. Today K+S AG operates two potash mines, the Verbundbergwerk Werra (Werra combined mine) and the Kaliwerk Neuhof-Ellers (Neuhof-Ellers potash mine). The Werra-Fulda potash district is once again a mining district in eastern Hesse and western Thuringia. Although much has changed, potash mining is still carried out.

The Wintershall potash plant is located in Heringen, and the landmark of the area is Monte Kali, a rather impressive mountain that is the spoil heap of the potash mines. The official name is Halde Heringen. In fact, two things were characteristic of the area, the spoil heaps and the cable cars that transported the mined rock and spoil. The first cable car was built as early as 1905 and the last remaining cable car was decommissioned and dismantled in 1991. Unfortunately, the spoil tips are not without their ecologic problems. The spoil is naturally very salty and rainwater dissolves this salt. Some of the salty water is collected, but some of it runs off above ground and some of it seeps into the groundwater. This leads to a high salt load, which is exacerbated by toxic additives from the mining industry.

The museum is currently closed due to the extensive energy refurbishment of the museum building. Better insulation, new heating, a solar system and other renovations are currently being carried out. The opening of the new entrance area on the Anger, Heringen’s large market square on the main street, is planned for 2025. This part of the building will house the tourist information centre, which will certainly be able to provide information on the progress of construction work by then. The reopening of the building is planned for 2027. There will probably be a large special exhibition first, and only then, probably in 2028, will the new permanent exhibition be opened. Until then, we can only recommend a visit to the Erlebnisbergwerk Merkers (Merkers Adventure Mine).