Abstract 2023

Abstract ITALIAN MINERALOGICAL MAGAZINE
nr. 1-2023

ANGELO DA COSTA
A
PIONEER OF THE MODERN
MINERALOGICAL
COLLECTING IN TUSCANY

Angelo Da Costa (1940-2022) was a master for many of the collectors who follow the pages of the Rivista Mineralogica Italiana, especially for those from his region: Tuscany. Angelo began to collect minerals between the 1960s and 1970s, experiencing the transition from the solitary pioneering period to the organized and participated one of the mineralogical associations. Angelo was a curious explorer and an excellent digger. In 50 years, Angelo has built up a wonderful regional collection based exclusively on specimens self-collected, exchanged or donated by friends. Hanging around Tuscany in search of minerals, he met several generations of collectors, first learning from the elder and then teaching the younger ones. Angelo left a memory of himself in all the people he met, but the trace he cared about most is certainly the selection of specimens from his collection acquired by the Museum of Mineralogy of the University of Pisa, where it will remain forever. Those minerals, in addition to being of considerable aesthetic and scientific value, will continue to tell the stories of his explorations for those who want to try to read the geological history of our planet.

THE DA COSTA MINERAL COLLECTION.
THE NEW ACQUISITION
OF THE NATURAL HISTORY MUSEUM OF THE UNIVERSITY
OF PISA

The mineral collections of the Natural History Museum of the Pisa University are composed by more than 20,000 specimens. Among them, mineral specimens from Tuscany are well-represented, owing to the interest shared by several mineralogists of the Pisa University for the sampling and study of the mineralogical occurrences of this Italian region. Angelo Da Costa previously contributed to increase the mineral collections of the Pisa University through some donations. For instance, he donated the exceptional aggregates of quartz crystals found at Mount Cascetto, in the Monte Pisano metamorphic complex, in 1995 along with Andrea Dini and Marco Lorenzoni. The Angelo Da Costa mineral collection was formed by more than 600 specimens mainly found in Tuscany; most of them were self-collected during a a collecting activity last for 50 years. The Natural History Museum a selection of 33 specimens accurately chosen from his collection. Several outstanding specimens from the Apuan Alps hydrothermal veins were collected by Angelo Da Costa. At the beginning of the 1970s, he discovered some vein systems in the Acqua Bianca valley, in north-eastern Apuan Alps. A very nice hematite specimen, with crystals up to 3.5 cm, and colorless crystals of quartz from these findings have been acquired by the Natural History Museum. Another hematite specimen, from a nearby locality (Vagli), was also added to the mineral collections of the Pisa University. Nice specimens from the old mines occurring in the southern Apuan Alps were also acquired:among them, baryte crystals from the Buca dell’Angina mine, cerussite from the Santa Barbara tunnel, in the Argentiera di Sant’Anna mining complex, aragonite flos ferri from the Canale della Radice mines, and two important specimens of smoky quartz from the Pollone mine. Angelo Da Costa also discovered some vein systems in the Monte Pisano metamorphic complex; two specimens of goethite after rhombohedral carbonates from the Vorno and Sant’Andrea di Compito vein systems are representative of these findings. Angelo Da Costa also explored the mineralogical localities of the Campigliese area. He found nice specimensof quartz and ilvaite crystals in the cavities of the hedenbergite + ilvaite skarns of the Temperino mine; three samples from these findings are now in the mineral collections of the Natural History Museum of the Pisa University. One of them is characterized by a thin coating of iron oxy-hydroxides on the quartz crystals, with a nice aesthetic effect. In the deeply oxidized skarns of the Buche al Ferro, Angelo collected one of the most representative specimens of aurichalcite, associated with colorless hemimorphite. Also this sample is now kept in the Museum’s collections. Some interesting specimens are from the Botro ai Marmi area: a 10-cm fluorite octahedron, a well-developed tabular crystal of allanite-(Ce), nice crystals of “scapolite” and arsenopyrite, a huge individual of “adularia”, and an aesthetic quartz specimen. Four specimens from the Colline Metallifere area were bought from the Da Costa collection. The most spectacular is a specimen of quartz from the Campiano mine, whereas a druse of amethyst quartz from the Gavorrano mine and of sulfur from the Niccioleta mine have only a regional significance. On the contrary, a quartz sample found by Angelo Da Costa within cavities of skarn bodies cropping out in the Val Castrucci area, close to the old mine of Fenice-Capanne, near Massa Marittima, has a very high quality. In the collection of Angelo Da Costa, there were several interesting specimens from other Tuscan localities: antimony ore deposits from southern Tuscany, minerals from the Pitigliano ejecta, gypsum crystals from several evaporitic outcrops, and specimens from the pegmatites of the Elba Island. Shiny stibnite crystals from the Pereta mine, related to the nice findings performed between 1979 and 1981, during the last mining activity at this locality, were acquired by the Natural History Museum, as well as a large specimen of sulfur from the nearby locality of Zolfiere. Another specimen of stibnite from the Montauto mine, not far from the more famous Tafone mine, was also obtained. A specimen f vesuvianite from Pitigliano and large crystals of gypsum from Triassic evaporites cropping out at Roccastrada were added to the Pisa University collections. As regard gypsum, Angelo Da Costa had collected a lot of very well-developed crystals from the Mio-pliocenic formations from several localities (Monti Livornesi, Gambassi Terme): one nice specimen from Gambassi Terme was bought by the Pisa University. Last but not least, a wonderful specimen of tourmaline from the findings performed in 1994 at Forcioni, in the Elba Island, was chosen for the collection of the Natural History Museum. This specimen and the exceptional finding are described in another paper in this issue of the Rivista Mineralogica Italiana.

BOULANGERITE – THE EXCEPTIONAL SPECIMENS FROM
THE BOTTINO MINE
(APUAN ALPS, TUSCANY)

The occurrence of sulfosalts from the Apuan Alps hydrothermal ore deposits has been known since the 19th Century and currently 25 sulfosalt species have there their type-locality. Several of them are very rare, as for instance the lead-antimony oxy-sulfosalts and oxy-chloro-sulfosalts from the Buca della Vena mine, the complex silver-lead sulfosalts from the Pollone mine, and the Tl-Pb-Hg-Ag-Cu-Sb-As sulfosalts from the Monte Arsiccio mine. However, one of the most significant sulfosalts from the Apuan Alps is boulangerite. Indeed, its specimens found at the Bottino mine can be considered among the best representatives of this species. The Bottino mine is hosted within the Paleozoic basement of the Apuan Alps metamorphic complex and exploited several ore bodies but the major production was obtained from the socalled Bottino ore body. This was represented by a strongly deformed and folded sulfide concentration cut by a shear zone during the Alpine orogeny; along this tectonic structure, sulfides were partially remobilized and reprecipitated. The Bottino ore body was exploited for 400 meters along strike and 350 m along dip, from the outcrops (at 525 m above sea level) down to the 170 m level. It was formed by two main ore shoots, the so-called Sansoni and Orsini columns. These high-grade zones were formed by massive sulfides (galena, sphalerite, pyrrhotite, pyrite) along with minor gangue minerals
(quartz, carbonates). Well-crystallized specimens were mainly collected at the hanging-wall of these two columns, where two different kinds of mineralized fissures occurred, i.e., shear and extension fissures. Both fissures probably formed during the late-stage evolution of the Bottino ore body, owing to the rheological contrast between ductile sulfides and brittle country rocks. Most of the historical specimens kept in the old collections (e.g., the Cerpelli collection) were collected in shear fissures, whereas mineral collectors, after the closure of the mine, were able to exploit a lot of extension fissures, because shear fissures were located at the hangingwall of the ore body that was completely extracted during the mining activity. On the contrary, extension fissures propagated within the barren country rocks and were not removedby miners during the mining exploitation. Boulangerite was found in both kinds of occurrence.
The actual identification of the plumose specimens of sulfosalts from the Bottino mine was possible only in the 20th Century, when Carlo Lorenzo Garavelli used X-ray diffraction to study them, identifying boulangerite. Previously, several different sulfosalts were erroneously reported (e.g., heteromorphite, jamesonite). For instance, the beautiful plumose specimens were usually labelled as jamesonite in old papers and collections. It is worth noting that no important boulangerite specimens dating to the mining period are kept in mineral collections, the only exception being represented by the specimen 17656 of the Natural History Museum of the Pisa University, previously belonging to the Cerpelli collection. However, also the quality of this specimen is lower than that of those found by mineral collectors during the last fourty years and carefully extracted from the fissuresof the Bottino ore body. The most important findings were performed during the 1980s in the Sansoni zone, and later between 2005 and 2011 in the Orsini zone.

FORCIONI - ELBAITE CRYSTALS FROM THE NORTHERNMOST
PEGMATITES OF SAN PIERO
(ELBA ISLAND)

In 1994, the careful exploration of the area to the north of Sant’Ilario in Campo (Elba Island) led to the discovery, in the Forcioni Valley, of a new pegmatite vein that had escaped the research of Luigi Celleri (the most famous digger of Elba pegmatites in the XIX century) and the many collectors who, in the past, had explored the area. The polychrome crystals of elbaite extracted from the cavities of this vein rival in quality and beauty with those found in the most famous places in the San Piero area. The Forcioni Valley is located much furthe rnorth than the classic localities of Grotta d’Oggi, Facciatoia, Fonte del Prete and Prado, and it was known in the past only for a few small crystals of blue beryl extracted from small pegmatitic veins. The Med-iterranean maquis north of Sant’Ilario, including the Forcioni Valley, was devastated by a great fire during the summer of 1993. Previously impenetrable areas became easily explorable. In the spring of 1994 one of the authors (A.D.), hanging through the carbonized vegetation, found a beautiful specimen of elbaite in green crystals. It was abandoned near an ancient trench excavated, perhaps by Luigi Celleri, near the locality of Casa Mastaglino in the Gorgolinato Valley. The following autumn, two of the article’s authors (A.+D. and M. L.) organized an expedition to the Gorgolinato Valley to follow up the traces of the specimen which was fortunately found. The old trenches
in this valley did not give good results and the exploration was extended to the north, in the nearby Forcioni Valley. One of the authors (M. L.), found small pieces of pegmatite with pink elbaite scattered in the soil of a small thermal fluids. The excavation of the vein was abandoned in January 1995 at a depth of about 3 meters. After that, the expert collector Federico Pezzotta continued the excavation during the Spring 1995, focusing on the southern part of the vein. Federico found a second columnar cluster of cavities from which he extracted some remarkable specimens with elbaite in green crystals. Also in this case, the termination of many crystals was corroded. Federico and Marco tried to deepen the excavation during the spring of 2006 but the results were disappointing. The vein tapered down and the granite host rock became extremely hard to remove. The pegmatite vein of Forcioni Valley represents the northernmost vein of the San Piero-Sant’Ilario pegmatite field to have provided beautiful elbaite specimens.

Rivista Mineralogica Italiana > Abstract Articoli