Gabbro, Rosignano Marittimo, Livorno Province, Tuscany, Italyi

Regional Level Types
Gabbro	Village
Rosignano Marittimo	Municipality
Livorno Province	Province
Tuscany	Region
Italy	- not defined -

Gabbro is the name of a village located on the Livorno Hills, in the municipal territory of Rosignano Marittimo. The name gabbro is used worldwide to indicate an intrusive igneous rock. The term gabbro, used originally by the Italian naturalist Giovanni Targioni Tozzetti (1751 and 1768) and brought into the international geological terminology by the German geologist Christian Leopold von Buch in 1809, comes from the homonymous village because of the presence of this rock in the ophiolite sequences found in the surrounding area.

Outcrops of serpentinites of the Allochthonous Ligurian Complex are typically found in the Gabbro area. In particular, an old abandoned serpentinite quarry is located in the vicinity of the old sports ground of Gabbro.

Grossular appears to be the main constituent of massive veins which intersect the serpentinite masses. It is normally associated with chlorite and lesser amounts of vesuvianite and titanite. On the contrary, andradite occurs on the walls of open lithoclases cutting the same rocks; it is associated with diopside and very rare vanadinite.

The following is a translation of https://parcoculturaledicamaiano.toscana.it/le-miniere,-le-mineralizzazioni-ed-i-minerali.php :

At Gabbro:

Mineralizations quite similar, albeit of a smaller extent, to those that were exploited in the mines of Campolecciano (https://www.mindat.org/loc-64339.html) and Macchia Escafrullina (https://www.mindat.org/loc-411075.html), affect the areas around the town of Gabbro.

These are magnesite and dolomite mineralizations and iron sulphide concentrations.

There are two most interesting locations: a mining prospect in Pian Cascianese and an old serpentinite quarry known as Buca Fonda near the mill of the same name on the Botro Sanguigna stream.

Already since the end of the 1800s, in the locality of Pian Cascianese, the presence of vein mineralizations has been reported, the origin of which is attributable to the hydrothermal action, in correspondence with the faults, of hot waters rich in carbon dioxide and hydrogen sulphide.

The distinguished geologist and naturalist from La Spezia Giovanni Capellini in an 1878 publication reported on a visit he made a few years earlier; he could observe: "... some works undertaken to search for iron ore, in the place called Piano Coscianese and Cerrette, just above the mill of the Sanguigna... The works, recently started, had already been abandoned; but the rocks cut for the research and the extraction of iron ore were still fresh and offered great interest to the naturalist".

Capellini visited two research tunnels and a 12m deep well dug following the course of a stream of compact limonite that gradually passed deep into unchanged marcasite.

The situation described by Capellini at the end of the 19th century still exists today and is practically unchanged: two small tunnels, one of which is accessible and the other with a partially collapsed entrance, open in the Pian Cascianese locality, together with a vertical shaft in which some walls show traces of manual processing are still present.

The well, originally filled with waste almost to the ground level, has recently been reclaimed by the owners and volunteers, removing and disposing of the waste until it intercepts one of the two tunnels at the bottom.
In the tunnels and in the well, the veins of iron ore, limonite, which originated from the alteration of the original iron sulphide, marcasite, are still clearly visible.

There are direct testimonies of a third gallery that tell of a long downhill gallery from which chalk would have been extracted; the only traces currently present that could be traced back to this structure are represented by a hint of the entrance, completely obstructed by blocks of rock, which could be collapsed or put in place to prevent access.
In any case, there is no trace of magnesite in the accessible tunnel and in the well, while fragments of this mineral in association with dolomite are found scattered in the surrounding soil.

In the vicinity of this site, just above the Botro Sanguigna on the right, is the old Bucafonda quarry where the serpentinite used as ornamental stone was extracted.

The quarry looks like an amphitheatre bordered by vertical walls surmounted by maritime pines and Mediterranean scrub, with a body of water in the lower part near the entrance where the excavations conducted in the past have left a depression delimited by smooth regular carved walls from the helical wire, the system then used to extract the stone blocks.

To manage this cutting system, some workers specialized in this type of activity had been specially brought from Carrara, where this particular extraction method was widely used for the excavation of the famous marble.
This method is based on the slow erosive action exerted by a woven wire rope (the helical wire) which carries water and silica sand as an abrasive. The wire is kept in motion by pulleys moved by a motor and is guided with pulleys generally positioned at a considerable distance along the perimeter of the quarry; the wire is made to slide on the rock to be cut where special "wells" are made, previously prepared next to the block to be isolated; in a few tens of days blocks of tens of cubic meters can be cut.

Along the edge of the quarry, you can still see the remains of some of the work with lengths of helical wire wrapped around the pulleys and the pitch with what remains of the motors and large pulleys that transmitted the movement to the wire.

The quarry was in operation from the postwar period until the 1970s by the De Ranieri brothers who also had a marble workshop in Livorno near the railway station and who also created the Palladian-type flooring in Via Grande in Livorno.

The extracted blocks were sent to Querceta where they were sawn into slabs for ornamental use, providing products of considerable value and beauty in terms of colour, veins and lustre; once an entire block was loaded onto a ship at the port of Livorno and shipped to America to form an altar.

The quarry is a very suggestive and unique environment, of considerable landscape and environmental value, of high interest not only for the naturalist; after years of neglect, it has been completely cleaned of large quantities of waste by its new owner, thus returning it to its original splendour again.

From a geological point of view, the quarry offers the possibility of a perfect observation and study of the numerous veins present, which show mineralizations very similar to those of the magnesite mines of the Fortulla valley.

They have a sub-vertical trend, north-south direction and are less than one meter thick; two different types can be recognized: one with magnesite and dolomite mineralization and another with opal and limonite.

The first consists of whitish, compact, porcelain-like magnesite cores, surrounded by green dolomite in beautiful zoned masses of mammillary structures; on the sides of this type of veins there are frequent spar-like dolomite veins, which contribute to making up a very striking and aesthetic whole. Other minerals found in this area are aragonite and marcasite, both in small idiomorphic crystals in the geodes of dolomite, and rarely opal.

The mineralization of the veins of the second type consists of brown opal with a resinous appearance and earthy limonite with salbande.

Limonite derives from the alteration of original iron sulphide (marcasite); this alteration process produces acid fluids that percolate and interact with the encasing rock, depositing white and yellow efflorescences, abundant in the summer season, consisting of the secondary minerals epsomite (magnesium sulphate heptahydrate) and aluminocopiapite (sulphate hydrate of iron, magnesium and aluminium).

Finally, with regard to this locality, it should be noted that there is evidence of the presence of a tunnel located under the quarry near the Sanguigna cave; ascertaining the presence or absence of the tunnel is nowadays practically impossible since the area is completely covered by the debris produced by the overlying quarry.

Another interesting place from a mineralogical point of view is the one near the old sports field of Gabbro; here, in the crevices of the serpentinites, some mineralogical species of secondary origin are found: garnets, diopsides and vanadinites.

Garnets appear in small crystals with rhombododecahedral dress, yellow colour and very accentuated lustre; as a whole, they form associations ("Druse") that are aesthetically very valid. The chemical-physical analyzes for their characterization indicate that it is an andradite garnet (calcium and iron silicate) of the topazolite variety.

Associated with garnets, thin prismatic crystals of diopside (calcium and magnesium silicate belonging to the pyroxene group) and, very rarely, hexagonal prismatic crystals of vanadinite (lead chlorine vanadate) can be found.

In the town of Gabbro, in the area of ​​the old wash houses, there are interesting quartz mineralizations and other mineralogical species.
They are found at the stratigraphic base of the neo-autochthonous sediments, near the contact with the underlying serpentine rocks. Their origin could be linked to the underground circulation of the same fluids that gave rise in the serpentinites to the extensive mineralizations of magnesite, dolomite and chalcedony that very widely affect the territory of the municipality of Rosignano Marittimo.

A first report of these mineralizations dating back to 1988 concerns the presence of quartz, chalcedony, opal and magnesite in small geodes in the layers of the sandstone formation of the Sanguigna stream.
The place of discovery is located on the eastern side of the hill on the top of which Villa Mirabella was erected.

Recent and extensive inspections conducted in the area have not shown even the slightest trace of this mineralization; people who have visited this place in the past years claim that it is a tiny outcrop, nowadays affected by a landslide and by weeds that have obliterated the vision.

Not far from the previous location, a mineralization of quartz and chalcedony has been found which has not yet been reported in the literature and therefore described for the first time here.

These are geodes of even decimetric dimensions, entirely covered with quartz as colourless or whitish crystals of variable dimensions but in any case not exceeding a few millimetres, with the prism very little or not at all developed.

The peculiarity of this mineralization is constituted by the fact that in some geodes there are two different generations of quartz.

The first generation is made up of druses with a mammillary appearance of generally colourless crystallines, directly implanted on the rock.

The second is formed by a kind of crust with a thickness of a few millimetres, located above the first generation of quartz, consisting of a veil of chalcedony and crystals of quartz similar to the previous ones but whitish in colour and not very transparent. This crust is perfectly modelled on the underlying mineralization while being able to detach itself quite easily.

The mineralized rock is made up of decimetric layers of fine-grained grey limestone, fetid on percussion, very compact, completely pervaded by geodes carpeted with quartz.

Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Gabbro,_Rosignano_Marittimo
Wikidata ID:	Q3756409

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