Lengenbach | History and Mining

The first references from Lengenbach area (literally the creek Lengen) dating from the first half of the eighteenth century. At that time, the area was not mined by their rare sulfosals but the interest was focused on the iron ores. In 1728, Mr. Courten, Governor of the Valais canton, hired two Englishmen, Mandel and Aston, in order to analyze the iron ore deposits of the Binn Valley.
These two Englishmen drilled a gallery to explore the site, so called “Engländer-Stollen”. They found pyrite crystals on dolomite. However the catholic inhabitants of the valley didn’t like at all the presence of two heretic Protestants in their valley, and in 1732 forced Mandel and Aston to leave the area.


Binnite and realgar. Crystal 5 mm (Binn Museum)	Sartorite and Hutchinsonite. Fv. 7 mm. Hospital coll.	Sphalerite with Pyrite. Fv. 4mm. J. Rosell coll. (LB1991)

That find was forgotten until the beginning of nineteenth century, when some rare and unknown species were founded in the “Engländer-Stollen”. The oldest known specimen from Lengenbach dates from 1797 and it is deposited in the Natural History Museum of Basel (Switzerland). The label describes the specimen as a "yellow arsenic, red arsenic and white iron on white dolomite, from Valais". It is: orpiment, realgar and sulfosalts on white dolomite.
In 1833, Charles Lardy managed the first scientific research on Lengenbach minerals, particularly realgar and orpiment. In 1875 A.A. Damour described the dufrénoysite, the first described sulfosalt from Lengenbach.

Some members of the Dolomite Company in the western part of the old quarry. The man standing right in the middle are expected to be the head of the Syndicat, Franz Jentsch (1868-1907/08). Natural History Museum of Basel - Dr. Paul Bohny - F.N. Ashcroft (London, 1906).

During the second half of the nineteenth century, lived in Binn a priest so called Father Walpen (1842-1904), which had a good knowledge on mineralogy and was very interested on local minerals. Thanks to his intellectual interest, in the year 1900 was funded the Dolomite Company, that began to extract minerals from Lengenbach. Well known Binn inhabitants became members of this society, like Franz and Leopold Jentsch (1868-1907/08 and 1870-1924, respectively), Leopold Tenisch (1869-1944) and as a mining director Anton Imhof (1864-1937). Thus began a golden age in the mineral research that lead until 1912.
It was during this period that Dr. R. H. Solly (1851-1925), an active mineralogist from London determined the following sulfosalts (in chronological order): seligmannite (confirmed by H. Baumhauer), liveingite, baumhauerite, lengenbachite, hutchinsonite, smithite, marrite, trechmannite and hatchite. In 1912 Lengenbach mineral supplies to the institutions and museums were stopped and after a short time mine works were completely give up. The mine was abandoned and avalanches filled the works with rocks and snow. This situation continued until II World War finished.

In 1945, Josef Imhof, son of Anton Imhof, restarted mining works at Lengenbach with the help of several workers. It was this year when they found the largest realgar crystal found in the mine till today: 7x3 cm (2.75x1.18 inches) and 90 grams, now is kept at the Natural History Museum of Berne (Switzerland).
This finding encouraged Josef to look for financial support. This "office" work produced its results in 1958, when Mr Glossglauser and Mr. Sinner, chairman of the Committee on Museums of Berne, provided the necessary money founds to reopen Lengenbach quarry.

		Thanks to that support, in 1958 was based the Lengenbach Mining Community (Arbeitsgemeinschaft Lengenbach, AGL). This community was funded by the Natural History Museum of Berne, the Mineralogical Institute of the University of Berne, the Bally Museum from Schönenwerd and Josef Imhof. Since then the Lengenbach deposit is worked only for research purposes and mineral collecting. In the first working days all the deposited sediments were removed. In a short time they installed belt conveyors and other structural elements. All that bored its fruits and quickly they found again already known species as baumhauerite, hutchinsonite, jordanite and lengenbachite, among others.
Lengenbachite partially covered by Dolomite crystals. Former T. Imhof coll. (1978) J. Rosell coll. (2008). Fv. 2mm.

But also new and world unique species were discovered giving them the name according with the person which found them: imhofite, nowackiite and sinnerite. From 1958 until the present all the LGB sulfosalts crystal parameters have been measured and all the structures and chemical composition described. All these achievements have been possible thanks to the AGL with the warm collaboration of many people. The director of all investigation research works has been Dr. S. Graeser.

In the early 80's, the mining activities in the quarry were increasingly problematic, partly due to technical reasons (working in a quarry with walls with 15 meters high was very dangerous) and partly due to changes in the mineralization because the arsenic content in the mined areas was gradually decreasing and therefore the most interesting minerals were virtually absent.
These factors lead to the idea of completely finish the works or continue the mineral research in another area nearby. However, in 1985 a lucky stroke changed completely the situation.
This year a giant rock block fell down from the highest part of the wall to the former quarry. When the block was fragmented it was evident that their sulfosalts content was extraordinary high. The scientific study of these minerals has led to determine at least three new sulfosalts: edenharterite, stalderite and erniggliite.
This found encouraged the AGL to continue the mining works in this new level. It is possible that in the next years this new level brings us even more mineral species. To be continued...