A new treasure from the Dolomites: Fiemmeite
A mineral species unknown to science was discovered in Val di Fiemme, Trentino (Italy) by the researchers of the MUSE – Science Museum (Trento, Italy). The new scientific treasure was named after its place of discovery: Fiemmeite. This is an extraordinarily important recognition considering that the last discovery in the Dolomites of a new mineral species was made more than two centuries ago.
“Today, there are just over 5,000 minerals known to science” – explains Paolo Ferretti of the MUSE – “not many, compared to the millions of living species. This means that finding a new mineral species is much rarer than discovering a new living being. What’s more, the fact that fiemmeite comes from the Dolomites, which is among the most studied regions in the world, makes this find all the more sensational. The last time the Dolomites were recognised with a new mineral was in 1815”.
Fiemmeite is an additional mineralogical element that enhances the unique concentration of geological, palaeontological, geomorphological and landscape features that earned the Dolomites the recognition as a World Heritage Site.
Finding a new mineral is not an absolute rarity. From 100 to 200 new species are discovered each year. But the fact that scientists have been studying the Dolomites since the 18th century is an important one to consider. The dolomite, the mineral after which the Dolomites were named, was dedicated to French geologist Deodat de Dolomieu in 1792. And it is since 1815, which is the year gehlenite was discovered at lake “Lago delle Selle” (Monzoni Mountains, Val di Fassa), that no new minerals have been discovered at the so-called “pale mountains”, excluding those that were already known but redefined as a result of systematic reviews, such as pumpellyite-(Fe3+), cabasite-Ca and dachiardite-Na.
The discovery and study were conducted by MUSE researchers Paolo Ferretti and Ivano Rocchetti, together with colleagues Francesco Demartin and Italo Campostrini of the University of Milan, who were expertly guided by local mineral enthusiast Stefano Dallabona (part of the group “Gruppo Mineralogico Fassa e Fiemme”). The mineral was officially recognised by the commission of the IMA (International Mineralogical Association), which is responsible for the nomenclature and classification of new minerals (CNMNC).
So what are the characteristics of fiemmeite?
Appearing to the eye with tiny blue-coloured lamellae, fiemmeite is an organic mineral belonging to the oxalates group, in this case a copper oxalate hydrate with chemical formula Cu2(C2O4)(OH)2•2H2O crystallizing in the monoclinic system. It is very rare and the few samples that were not analysed to determine the new species are now part of the collections of the MUSE and the Department of Chemistry of the University of Milan. Fiemmeite is found within carbonised tree trunks, which abound in the basal part of the Val Gardena Sandstone, a sedimentary formation that originated in a river environment in the Upper Permian period about 260 million years ago. The Permian-Triassic stratigraphic interval has been in the sights of geologists of the MUSE and the University of Innsbruck, involved in a research project that has led to internationally-acclaimed results in the field of palaeontology.
Discovery site: The mine of San Lugano in the municipality of Carano
The mine was operated until the period between the First and Second World Wars and today the only evidence of its existence is a collapsed airshaft entirely covered by debris. The collapsed entrance to the mine is found a few metres below. The small mine could be accessed up until 30-40 years ago and consisted of a horizontal tunnel intercepted by an airshaft connecting this level to the surface (probably for ventilation). Copper minerals (chalcocite, tennantite, covellite) concentrated within the site’s abundant carbonised wood were mined here.
Study of fiemmeite
Fiemmeite’s discovery is the most important result of a research project that MUSE has been involved in since a few years aimed at the study of sites in Trentino-Alto Adige that are of interest from the viewpoints of mineralogy and mining archaeology. Analysis of samples gathered at the Mine of San Lugano with MUSE’s SEM-EDS equipment and the Raman spectrometer of a collaborator (Ivano Rocchetti) immediately led to the understanding that we were dealing with minerals whose characteristics were very different from any known mineral species. Further diffractometric analysis at the Department of Chemistry of the University of Milan by Francesco Demartin and Italo Campostrini made it possible to determine the structure of these samples, which were found to be oxalate minerals. Three occur at San Lugano, all of which are copper oxalates: middlebackite (recently discovered in Australia, in 2016), moolooite, and fiemmeite, an absolutely new mineral in the world, allowing the scientists who made the find to name the species after the Val di Fiemme. To date, fiemmeite has not been found in any other part of the world and the San Lugano Mine is its type locality. The occurrence of these rare oxalate minerals at San Lugano makes it a geologically singular location at a worldwide level.
Investigating this location is just the initial stage of a study that we are confident will provide extremely valuable information about our past environments.
The pathway that led to the discovery of fiemmeite was born out of a close collaboration between the community of mineral enthusiasts and research institutions (scientific museums and universities).