The waters of this spring which are used traditionally by the local population for their therapeutic effects on dermatological disorders, emerge from pliocenic cover sediments (at a depth of approx. 230 meters under sea level) and are rich in gas and calcium carbonate. The waters rise through specific fracture lines and along the Iano-Villa Cozzano fault. The high salinity levels and the emergence temperature (23°- 24° C), indicate deep genesis. Together with the water, the subsurface gives off a considerable amount of carbon dioxide; this permits the transformation of soluble calcium bicarbonate into insoluble calcium carbonate which flows out to cover the ground with huge deposits of white or pale yellow travertine.
Inside the fractures there are veins of calcareous alabastrite and alabaster (onyx marble); the latter is used for the production of hand crafted decorative and ornamental items.
Palaeozoic schist outcrops are rocks identified by rows of parallel layers of alternating black clay schist with very fine grain grey arenaceous schist.
The scientific importance of these outcroppings lies in the large number of animal and plant fossil remains which have permitted calculations of the formation period.
The main plant species which have been found are typical of an equatorial climate, and this is a reliable demonstration that the region that belonged to the former continent called Pangaea was close to the Equator. The alternating clay-sandstone layers clearly indicate that this was a marine environment where the materials were deposited during transportation from the sea to continent.
This characteristic led to mining attempts in the past in the Palaeozoic schists (1850-1928). Between 1926 and 1930, following the setting up of the Fuel Commission, a range of deep exploration drillings were carried out aimed at discovering and mining carbon fossil, but these also produced negative results.
This whole area is extremely important from a geological and mining point of view.
During the first half of the 20th century drilling tests were made for research purposes; results showed the existence of a reversed stratigraphic framework (fold) and these were also confirmed after the discovery of hot thermal waters (38°C) in the subsurface. This area has also been subjected to exploration and mining activities as can be seen in the previous mine at Torri di Iano, famous for extracting antimony red, the mineral used to produce mercury.
The mine exploitation began in 1887 with the digging of the Savi Well (Pozzo Savi: 50 metres deep) and the Sfondato Well (Pozzo Sfondato: 73 metres deep). The mining activities beginning from the wells, were performed through a man way set on three distinct levels from which various galleries or tunnels were dug. Among the main work performed in the Iano area was the digging of the communication tunnel between the Savi Well and the old mine, through a gallery that demonstrated the continuation of the main layer of antimony red from the old mine and the existence of a new layer of bituminous black clay. The Savi tunnel which ran in a direction practically parallel with the stratification, followed the antimony red vein until a fault throw caused it to disappear. Today, the site still conserves two entrances to sub-horizontal tunnels. It is also possible to identify the exact position of the Savi well, currently filled with debris and the location of mesothermal water and gas emission.
The Red Water spring surfaces at a height of approx. 295 metres above sea level at a fault in constant dislocation with the Verrucano outcrop.
The spring is classified as a "contact spring", the waters gush freely towards natural existing impluviums downstream at a temperature of approximately 15° C.
The water content has medium to low salinity levels and can be classified as sulfate-alkaline-terrous water.
This is a water which infiltrates through the relief of Poggio dei Cipressini, and identified for its circulation which is presumably superficial and with a minimum influence of deep hydrothermal fluid flows.
The tectonic rise (Horst) where Poggio Spadone is located has provoked Palaeozoic schist outcropping revealing the oldest rocks with highest mineral contact in Tuscany, represented by carboniferous schists.
In this area the contact between the ancient subsurface rocks and the more recent pliocenic deposits can be clearly seen (see photo). It is easy to identify the development of the Pliocene sea with a paleogeographic environment which is totally different from that of today.
The area also shows strong buhrstone outcropping that feeds a deep thermomineral system.
Near Pietrina are the Bagno and Pozzaie sulfurous springs containing the thermomineral waters described above.
The ex-quarry in Montignoso is composed of three types of stone: Serpentinite, Gabbro and Diabase.
The most common is Serpentine with outcrops directly in the quarry area, whereas the Gabbro can be found in small outcrops inside the Serpentinite cluster.
Other formation outcrops can be seen in areas surrounding the quarry, mainly composed of Calpionella Limestone, Clay, flaky Marl, and Palombini limestone.
Serpentine was used in ancient times as a decorative material in building construction, and today is used for road paving.
Because of its special topographic position, the ex-quarry provides one of the most magnificent views over the whole Gambassi Terme area, where it is possible to look southwards and even see the magnificent hills of Volterra.
L'arte di lavorare le pietre dure semipreziose ha un'antichissima tradizione in Firenze.
Nel corso del XVI secolo grazie all'amore di Cosimo I de' Medici per questa lavorazione, nacquero a Firenze le prime botteghe granducali dove si producevano oggetti nelle più pregiate pietre dure. La stessa passione fu trasmessa al figlio Francesco il quale dette vita alla più celebre lavorazione del mosaico fiorentino ovvero della "pittura di pietra", una particolare tecnica di commessa delle pietre che accostate con commettiture invisibili vanno a formare, con i colori naturali delle pietre, paesaggi e nature morte.
Fu nel 1588 che Ferdinando I de' Medici dette stabile organizzazione ed ordinamento a queste botteghe creando l'Opificio delle pietre dure. Fu istituito nel 1588 nell'ex-convento di San Niccolò dal Granduca Ferdinando I de' Medici come manifattura di opere in pietre dure, la cosiddetta arte del commesso fiorentino, con la quale si realizzano tutt'ora splendidi intarsi con pietre semipreziose
Il commesso a differenza del mosaico non usa tessere geometriche, ma intaglia pezzi più grandi, scelti per colore, opacità, brillantezza e sfumature delle venature, creando un disegno figurato. Si realizzarono così opere d'arte di straordinario valore, dai mobili a oggetti vari, fino a copie perfette di pitture da appendere, che oggi arricchiscono i musei di tutto il mondo testimoniando la genialità e la tecnica degli artigiani fiorentini.
L'Opificio Tosco Ticciati utilizza da sempre procedimenti di lavorazione che rispettano e conservano nel tempo le tecniche tradizionali pur innovandosi sia tecnologicamente che nei materiali.
Ogni fase della lavorazione viene eseguita internamente all'Opificio, dallo stoccaggio dei materiali, costantemente approvvigionato per avere in qualsiasi momento disponibilità della pietra, al taglio del grezzo, al mosaico fino al confezionamento dell'oggetto.
L'Opificio opera ed è conosciuto sia a livello nazionale che internazionale, e le sue opere sono particolarmente apprezzate in tutta Europa, negli Emirati Arabi e negli Stati Uniti d'America.