Lengenbach, rare minerals in Switzerland

In the Swiss region of Valais (Wallis) a mine known as Lengenbach is “exploited”. From this small quarry, with a few more than 10 meters of mine face, minerals are not extracted for industry, but for research.

The exploitation works, which began in the s. XIX, are carried out in Triassic dolomites, rich in sulfosalts of Pb, Tl, Ag, and Cu, very rare worldwide, along with numerous other interesting and aesthetic mineral species. Of some of these sulfosalts a single specimen is known. It is the type locality (TL) of 46 different mineral species, making it the fifth most prolific locality in the world (TL: indicates that a mine is the first place in the world where a certain mineral species has been described).

The minerals mined in Lengenbach are meticulously numbered and registered, allowing in the future knowing from which area and when they were mined. In the summer months, when the snow does not cover the deposit, the extraction is methodically worked. Once dolomite is crushed and reviewed under the loupe, the discarded rocks are dumped in a dump where many collectors reduce the blocks to gravel. As a curiosity, some of the new minerals have been determined from pieces collected in this snowy white dump.