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Abstract 2021

Rivista Mineralogica Italiana > Abstract Articoli
Abstract ITALIAN MINERALOGICAL MAGAZINE
nr. 1-2021
MINERALS OF THE
“HISTORIC” QUARRIES OF TRASQUERA
VAL DIVEDRO- CAIRASCA (VB)


This  article  describes  a  number  of characteristic minerals, found in the abandoned  quarries  of  Antigorio orthogneiss,  locally  known  as  “serizzo” located in the municipality of Trasquera, in Divedro Valley. These quarries were exploited until the early 1970s. During several visits, made in the 1990 , these quarries have pro- vided good mineralogical specimens of “apatite”, anatase, brookite, epidote, heulandite-Ca, stilbite-Ca and titanite.  Although  less  frequently than in the past, it is still possible to find good specimens today.

GYPSUM CRYSTALS ON NATURAL CLINKER FROM THE SANTA BARBARA MINE, CAVRIGLIA

The spontaneous combustion of lig- nite and the transformation (T> 800 ° C) of the clayey host rocks into linker is an extremely widespread phenomenon in nature but little known among geologists and mineral collectors. Lo- cally, temperature may exceed 1200°C and  host  rocks  can  melt  producing small  flowing  volumes  of  lava  called “paralava”.  Natural  clinker  is  a metamorphic rock while paralava can be considered  as  a  true  magmatic  rock. Thanks  to  the  high  SiO2 and Al2O3 contents in clay, the resulting natural clinker  and  paralava  consist  usually of  an  assemblage  of  aluminiferous clinopyroxene and spinel, fayalite, se- kaninaite  (Fe-cordierite),  mullite  and sulfides.  When  the  host  clay  is  rich in  calcium,  an  even  more  complex paragenetic  assemblage  can  form  including  rare  minerals  like:  indialite, ferroindialite,  kirschteinite,  melilite, kalsilite,  fresnoite,  kinoshitalite,  srebrodolskite, esseneite, barioferrite and ellestadite. The color of natural clinker and paralavas range from orange-red to brownish-black  strongly  contrasting with the grey color of the original un- heated clay. Until 1994, Santa Barbara mine (Cavriglia, AR) exploited a large lignite deposit hosted by Pliocene clay (Argille  di  Meleto  formation).  The lignite produced was mainly used in the nearby thermal powerplant while natural clinker was utilized for paving mining  tracks.  In  1957,  exploitation switched from underground to open pit operation and large outcrops of lig- nite and natural clinker/paralava were progressively exposed on the surface. Combustion  of  lignite  was  a  spon- taneous process in this area and was described by the early naturalists since the XVI century.One of the authors (LP) was hiking in the upper part of the open pit during the spring 1973. He stopped in front of a bench made by orange-red natural clinker and could observe numerous lustrous, acicular crystals covering the rock. Prismatic and acicular crystals of gypsum up to 15 cm in length lined the  fractures  of  the  rock.  Beautiful aggregates of crystals stood out on the red-brown-black matrix made of natural clinker. The mining activity proceeded rapidly and, in a frantic race against time, Leo managed to extract few hundred specimens with magnifi- cent gypsum crystals. Since many years the mine has been abandoned and new findings of gypsum in the few remaining outcrops of red natural clinker must be considered rather unlikely.
THE OLD MINES OF GIUMEGLIO NEAR POPIGLIO (PISTOIA)




The Pb-Zn old mines of Giumeglio are one of the relics of the historic mining activity located in the Pistoia province  (Tuscany).  They  were  described by Antonio Matani in 1762, their  mineralogy  was  studied  only recently.  In  this  paper,  new  historical and mineralogical data are given. Primary ores are represented by galena,  sphalerite,  and minor  pyrite. The  sulfide  assemblage  is usually altered  into  secondary  minerals like smithsonite,  hydrozincite,  anglesite, and hemimorphite. In addition, lemon-yellow coatings  of  greenockite/ hawleyite are relatively common.
BEYOND THE BAZZITE – OTHER NEWS IN THE AMBIN MASSIF (TO)


The exploratory tunnel of “La Maddalena” (Chiomonte, Susa Valley, Italy) is the Italian shaft of Ambin base tunnel for the new international line Turin-Lyon.  The  tunnel,  diameter 6.3 m and about 7000 m long, was excavated by an open TBM and has the purpose of investigate the deep- est  part  of  the  project  (more  than 2000 m of coverage). In 2016 RMI published a first article about the discovery of bazzite in an alpine cleft at pkm 0+980. Apart from that finding, other mineralogical samples were collected  during  the  excavation  of  the tunnel. This article retraces the excavation and describes the species recognised and collected up to pkm 7+020, the end of the exploratory tunnel.
Abstrat ITALIAN MINERALOGICAL MAGAZINE
nr. 2-2021
MIMETITE FROM VALSASSINA, THE CONTRA VALLEY MINE


The Contra Valley mine, near Primaluna, Valsassina, represents the best collecting site for mimetite in Lombardy. This lead arsenate occurs in very nice specimens showing yellow or green hexagonal prismatic crystals, often forming aggregates of hundreds of small crystals, covering large areas of the specimens. They are aesthetically appealing even if not ob- served under a binocular microscope. The article deals also with several oth- er minerals, associated with mimetite, which were collected during years of research done by the authors.
HAÜYNE OR LAZIALITE?


This article explains how and why haüyne, a typical mineral of Lazio, should have been called lazialite, a name attributed by Father C.G. Gismondi to the mineral he discovered in 1803, instead of ignoring any priority and naming it haüyne by T.C. Bruun de Neergaard in honor to René Juste Haüy in 1807, all that without even Haüy´s approval. This article demonstrates how the sample existing at the Muséum na- tional d’Histoire naturelle in Paris cannot be the holotype as well, and how the type locality is also wrong,being not Monte Somma-Vesuvius (Naples, Campania), but the crater of Nemi (Rome, Lazio). A recent personal communication from M.E. Back to V. Nasti (2019-2020), con- firms that in the 2022 edition of the well-known “Fleischer’s Glossary of Mineral Species”, at least the type lo- cality will be corrected, from Monte Somma-Vesuvius to Nemi , without giving the mineral its original name back, and therefore without doing justice to Gismondi.
MERLINOITE, A NEW FIND FROM TREVIGNANO ROMANO.


This article describes a specimen of merlinoite, occurring as microscopic, radial aggregates of prismatic crystals, found in a leucitic rock from Fosso Fossaccio near Rome. This is a new locality for this rare zeolite group mineral. Merlinoite has been studied and identified  using  Scanning  Electron Microscope (SEM) and single crystal X-ray diffraction.
SMOKY QUARTZ FROM GALLURA, SARDINIA


Gallura is a subregion in north-east- ern Sardinia. Large part of the terri- tory, from a geological point of view, is characterized by granite rocks belonging  to  the  Sardinian Corsican Variscan  batholith.  This  article  de scribes the most important finds of smoky quartz specimens, reaching up to up to eighty centimeters across and weighing over 50 kg.
These  crystals  occur  in  pegmatite pockets. The research of the pockets was mainly focused on several active and abandoned quarries, located in the Gallura subregion, which include four different areas where is still possible to find quartz crystals within peg- matite pockets.
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