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Miner with giant clear halite cubes

Photo : Erlebnisbergwerk Merkers

To view spectacular 3D - panoramic images of this site, please click here.


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Rocksalt - Steinsalz - Sel roche - Sal

Europe : Germany : Halite (rocksalt) crystals up to 1,10 m in Merkers Potash mine

Coordinates : 50°49'N , 10°07'E : Merkers potash mine, Wartburgkreis, Thuringia, Germany

Giant crystals often occur in remote areas, which are difficult to visit even these days. Others are protected with only very restricted access or are on private property. Or they are simply mined out since long time. The Merkers potash mine is different. If you feel in the right mood to experience an outstanding underground mine, you can go down the Merkers shaft. Apart from the thrill of experiencing a preserved potash mine with its fascinating machinery and the reconstructed "gold vault" of the Third Reich you are allowed to have a good look into the largest known salt crystal cave in Middle Europe.

Halite salt rock is generally a very ductile type of rock, that is, under pressure it tends to flow quite easily. An old stope in a salt mine may completely shrink to a mere small hole in just a hundred years time due to salt flowing. So the miners in the 750 m deep Merkers mine were quite surprised when they found a large natural cave at that depth. More - the cave was partly filled with giant halite cubes up to more than 1 m edge length.

Knowing, that the government of socialistic East Germany always was keen to sell outstanding mineral specimen in exchange for hard Deutschmark to the west, the miners deciced to seal off the opening to the cave and wait for better times.

After the collapse of the GDR in 1990 the cave was opened again and, while potash production in the mine was curtailed and finally stopped, it was decided to turn the whole mine into a public museum. So here we are : one of the very few giant crystal localities which is a dedicated tourist attraction : the Erlebnisbergwerk Merkers.

The formation of this extraordinary halite cubes is - notwithstanding their size - quite simple. Whereever there is free space in a salt mine, the ubiqitious migrating salt brines tends to crystallize on the walls of this space. Mostly these crystals are only small due to the small space available. In this case the available space was large and so the crystals could grow to giant dimensions, not even filling up the whole void.

Finally it has to be said, that similar halite cubes were apparently found in other salt deposits as well. RÖSLER (1980) notes 'salt cubes of 100 cm' from the Allertal potash mines in northern Germany and from Detroit / USA, but dont give any closer details. More information is available about giant "golden" halite cubes in New Mexiko, which can be found here.


The Merkers Mine in a nutshell :

Mineralogy :

Halite xx in anhydrite/gypsum cave

Crystal Size :

1,10 m cubes confirmed

Geology & Origin :

crystallisation from saturated salt brines in anhydrite void

Current status :

Museum mine, tourists are welcome to visit the crystal cave

Remarks :

A rare opportunity to visit a potash mine and giant crystals 750 m underground


Other notable & famous halite localities

- "Golden" cubes to 1 m size has been discovered in the Carlsbad potash district, New Mexico, USA, back in the 1960. For more information about this spectacular find please look here.

- Other large halite cubes have been rumoured to occur in other german potash mines as well, such as the long abandoned Allertal mines. These mines are however definitely flooded these days.

- rose to pink coloured, often skeletal cubes, are formed in recent salinas such as the Searles Lake, San Bernardino Co, California. The colour is due to haliforom bacteria and often starts to fade after some time.

- Fine transparent halite cubes up to 0,5 m size are known from the famous Wieliczka mines near Krakov, Poland, a world heritage site.


Photo documentation work in the Merkers Crystal Cave

Photo : Frank de Wit


Frank and the giant halite cubes

Photo : Thomas Witzke



Resources and relevant weblinks :

For more information on the mineral halite / rocksalt please look at, Webmineral and the german Mineralienatlas.

The most comprehensive publication about the giant salt crystals is :

PIPPIG, M. (1992) : Über das Vorkommen einer Kristallsalzschlotte im Kalibergwerk Merkers

in : Kali & Steinsalz, Bd. 11, Heft 1/2 p.2 - 7

To view 3D - panoramic images of the cubes, please click here.

To view many other photos from our March 2005 documentation trip, please click here

Furthermore you can find information about the Merkers mine and its fascinating history on their own website.




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