Lurisia Mine (Lurisia autunite deposit; Nivolano Quarry), Lurisia, Roccaforte di Mondovì, Cuneo Province, Piedmont, Italyi

Regional Level Types
Lurisia Mine (Lurisia autunite deposit; Nivolano Quarry)	Mine
Lurisia	Village
Roccaforte di Mondovì	Commune
Cuneo Province	Province
Piedmont	Region
Italy	- not defined -

Uranium mineralisation in Permian porphyroid rocks (i.e. acid metavulcanites with porphyritic texture), known in the old literature as "besimaudites" (Internal Ligurian Briançonnais Domain).

In 1912, a yellow mineral occurring as crystalline crusts on the cleavage planes of slabs of the "besimaudite" rock extracted for building purposes at Nivolano quarry, uphill the village of Lurisia, was brought to the attention of Gabriele Lincio by Pia Bassi, student at the Institute of Mineralogy, University of Turin. The mineral was identified as autunite by Lincio (1913), who measured the tetragonal crystal morphology and uniaxial refraction indices, performed several chemical tests, which include a quantitative determination of UO3 (60.57%) and a comparison (darkening of the photographic film) between the Lurisia ore and the uraninite-rich pitchblende from the well-known locality of Sankt Joachimsthal (now Jáchimov). The water of the spring Nivolano, pouring out of "besimaudite" and encrusting the stone layers with autunite, attracted also the attention of the scientists as a potential lavish source of "émanation" (radon).

During World War I the Lurisia autunite occurrence became an object of intersest of the Office for Inventions and Research, Ministry for Weapons and Munitions, mostly composed of physicists and chemists kept away from the front and set into the rear. Although they also aimed at finding suitable sources of radium, considered a very powerful means of cure, their priority was given to helium, a light gas that chemists would possibly draw out from vapours arising from radioactive thermal springs, where it is intermixed with "émanation" (radon). Helium, in their expectations, was a more important commodity than radium was, as it could substitute for hydrogen as non-inflammable lifting medium for balloons and dirigibles, at that time fundamental strategic implements for the air survey of the battlefront. In order to evaluate the possible sources of these substances, the Italian Army invited Marie Curie (Marie Skłodowska-Curie) in Italy, giving her the role of counsellor (Simili, 2013; Mottana & Nastasi, 2015).


Marie Curie with a little group of scientists enrolled in the Italian Army (Vito Volterra, Alberto Pelloux and Camillo Porlezza) visited the Lurisia site (Nivolano quarry) on August 15-16, 1918. Marie Curie's measurements confirmed that water of the Nivolano spring is strongly radioactive, but her real interest was autunite, as a potential source of radium. Millosevich (1919) published an evaluation of the geological asset of the area and of the related economical potential. In his essay he gave the first quantitative data on the real amount of radium present in the orebody. For first quality ore: 1.3 x 10˄-7 g Ra over 1 g autunite (thus, confirming the results obtained independently by Marie Curie in Paris and Camillo Porlezza in Pisa on selected crystals: 1.3 x 10˄-7 g Ra), and 0.62 x 10˄-7 g Ra for autunite just scraped off the rock schistosity planes. According to Millosevich, the Lurisia ore could be considered excellent and rich in radium as much as the ones from Guarda District in Portugal, at that time the most productive source available to the Entente states. Although World War I had ended, Sankt Joachimsthal was not yet open to interstate commerce; thus, Millosevich pushed exploration at Lurisia by drilling galleries, supported by the geologist Secondo Franchi, who too had studied the geological structure of the area (Franchi, 1919). The description of torbernite, in association with autunite, limonite and Mn oxides (Bellini, 1920), confirmed the superficial formation of both uranium minerals in a water-rich environment. Towards the end of 1921 the Royal Commission for the Study of Radioactive Materials, chaired by Volterra and assisted by Millosevich, decided to survey the Lurisia uranium prospect. The exploration began in late 1921 and ended in October 1923 after excavating only a 120-m-long adit: the ore found was too little. In November 1927, the company of the two Genoese entrepreneurs Garbarino and Sciaccaluga, mainly interested in the exploitation of the radioactive mineral water for therapeutic purposes, was granted a prospecting permit for the Nivolano area. A second campaign of scientific explorations started in January 1933 (Corradi, 1934) within the frame of the autarchic policy. Further analyses for radioactivity were carried out (Francesconi and Bruna, 1934) and a complete mineralogical and geological description was made (Pelloux, 1934 and 1942). Indeed, during the 1930s a system of galleries and pits was excavated and crossed the entire mountain slope from Nivolano to the nearby Asili gulley. Once again, the results were unsatisfactory and the State renounced definitively to the Lurisia mine rights in 1939. At the same time, the rights on the entire mining area (561 hectares) were conferred to Garbarino & Sciaccaluga Company. The company was able to build a thermal resort quickly, opening it during the first years of World War II. A water bottling plant was set up in the postwar period. The Lurisia spa resort and bottling plant, however, draw their water from a nonradioactive spring, named Santa Barbara, since the Nivolano (generally known as Garbarino) spring is far exceeding the limits about water radioactivity, not only for bottling but also for direct use. Indeed, the radioactivity of the Garbarino (Nivolano) spring is 13,219 x 10˄6 Bq/l, the second highest in the world.

At Lurisia autunite invariably appears as tabular crystals, usually square and rarely octagonal, that only seldom exceed 3 mm on edge and 1 mm in thickness. Their colour ranges from sulphur-yellow to yellow-green. According to Porlezza & Donati (1922) and Francesconi & Bruna (1934), the different yellow-green shades are related to the content of As5+ substituted for P5+. Interesting specimens, in which tiny tabular crystals of autunite are disseminated on the surface of black mammillary concretions of manganese oxides, were found during the 1970s in an old exploration adit. Some collectors improperly identified such specimens as "tucholite".
Torbernite is less common than autunite and forms tiny crystals, usually tabular and rarely dipyramidal, up to 1 mm in size.

Other Regions, Features and Areas containing this locality

References