The "Stella Polare" Expedition (1899-1900): Study and Enhancement of the Rock Collection

The "Stella Polare Expedition" collection represents the rocks collected during the attempt to reach the North Pole in the winter of 1899-1900 by the Italian explorer Luigi Amedeo di Savoia, better known as "Duca degli Abruzzi". The collection is currently kept on loan at the Regional Museum of Natural Sciences in Turin and belongs to the series of mineralogical-lithological collections owned by the University of Turin. It is unique from both the historical and the scientific points of view. It mainly consists of effusive magmatic rock samples, such as tholeiitic basalts, basaltic andesites and sub-intrusive rocks, such as dolerites. In the collection are also present sedimentary rocks (i.e. sandstone, siltite, jasper), high-grade metamorphic rocks (i.e. granulite) and a good number of mineralizations (i.e. quartz, opal, calcedony, calcite and zeolite), probably included within the effusive magmatic rocks in the form of veins or amygdales. From the geochemical point of view, it was possible to classify volcanic rocks as effusive products belonging to the sub-alkaline subduction-related tholeiitic series, which in turn can be distinguished into two main types, corresponding to basalts and basaltic andesites. Furthermore, the dolerites show geochemical features compatible with an oceanic environment analogous to Ocean Island Basalts, not or scarcely contaminated by the continental crust, in agreement with the geographic and geological position of the Franz Josef Land, located at the border of the Eurasian continental shelf and close to the Nansen depression ocean floor. The rediscovery and study of this collection have made it possible to enhance historically, and to deepen, with a scientific approach, the study of materials that would have been difficult to retrieve.