Tolfa

The necessity for the addition of a portion of alkali in order to form alum is also confirmed, said Lavoisier, by a very interesting observation of M. Monet [A.-G. Monnet (1734-1817)] on the earth extracted from the alum at Tolfa the chemical examination which he made of specimens of this earth, brought from Italy by M. Guettard, showed him that it contains a portion of fixed vegetable alkali already formed. It is doubtless to this alkali that this earth owes its property of furnishing... 

Father Athanasius Kircher said that the phosphorus was made by pulverizing the Bologna stone, mixing it with white of egg or linseed oil, and calcining it in a special furnace. He found specimens in the alum mines at Tolfa (59). Biographical sketches of Father Kircher were published in The Hormone in 1934. (109) and in the Journal of Chemical Education in 1955 (139). 

Antoine Baum6 stated that die purest alum came from Civita Vecchia near Rome and that a good grade of it was also made at Solfatara. He based his account on die Abbe J.-A. Nollet s description, read before the Academie des Sciences in 1750, of his visit to the Solfatara alum works and on the Abbe Mazeas s memoir on the alumte mines of Tolfa, Italy, and Polinier, Brittany, which was pubhshed in volume five of the Savants etrangers (148). 

The Tuscany Magmatic Province (Fig. 2.1) comprises several mafic to silicic intrusive and extrusive centres scattered through southern Tuscany and the Tuscan archipelago. The silicic rocks of the Tolfa-Manziana-Cerite area, north-west of Rome, and a mafic ultrapotassic dyke from Sisco (Corsica) are also traditionally included into the Tuscany Province (Poli et al. 2003). 

Tolfa-Manziana-Cerite 3.5 - Multicentre complex made of trachydacite to rhyolite lava flows, domes and pyroclastic flows. 

Tolfa-Cerite + Vercelli seamount Torre Alfina O Capraia... 

Silicic volcanics occur as lavas at San Vincenzo, Roccastrada, Monte A-miata, Monti Cimini and Tolfa-Manziana-Cerite complex. Pyroclastic rocks are scarce or absent, and a few ignimbrites only occur at Monti Cimini and Cerite complex. Silicic intrusions crop out in the islands of Elba, Montecristo and Giglio, and at Campiglia and Gavorrano in southern Tuscany. Other granitoid bodies occur as seamounts in the northern Tyrrhenian Sea (e.g. Vercelli Barbieri et al. 1986) and as hidden intrusions in several places of southern Tuscany (e.g. Franceschini et al. 2000 Poli et al. 2003). 

Magmatic centre Roccastrada San Vincenzo Tolfa Manziana Mt. Amiata Mt. Cimini... 

The Sabatini Volcanic District developed between about 0.8-0.6 Ma and 40 ka over a wide area located just to the north of Rome. Volcanism was predominantly explosive and generated widespread pyroclastic deposits with only minor lava flows, which were emitted from a large number of centres including several calderas (e.g. De Rita et al. 1983, 1993). The vol-canism occurred along a zone of crosscutting NW-SE and NE-SW faults (Di Filippo 1993). The Sabatini rocks rest over the same type of sedimentary bedrocks as at Vico, as well over the acid volcanics of Tolfa-Manziana-Cerite complex of the Tuscany Province. 

Fig. 4.14. Schematic geological map of Sabatini district. Simplified after Conti-celli et al. (1997). Numbers indicate various activity phases. Vertically mled areas west of the Bracciano Lake are Tolfa-Manziana-Cerite outcrops.

Clausen C, Holm PM (1990) Origin of acid volcanics of the Tolfa district, Tuscan Province, central Italy an elemental and Sr-isotopic study. Contrib Mineral Petrol 105 403-411... 

Field, C. and Lombardi, G., 1972. Sulfur isotopic evidence for the supergene origin of alunite deposits, Tolfa District, Italy. Miner. Deposita, 7 113—125. 

Pope Pius 11 described the origin of this industry. He stated that in May 1462, Giovanni de Castro, of Padua, whilst travelling over the mountains of Tolfa, observed a plant which he knew also grew on the alum mountains of Asia Minor. This led him to look... 

Klaproth analysed datolith, gypsum, and barytes. He missed the fluorine content of apatite, which was detected by Pelletier, but he detected sodium in cryolite and the fluorine content of teeth and fossil ivory, confirmed by Berzelius. He showed that native iron is free from nickel, which is contained in meteoric iron, and analysed chrome ironstone. He described the manufacture of alum at Tolfa. He confirmed (1801) an observation of Kennedy of Edinburgh (1797) that basalt contains soda, and discovered potash (previously regarded as confined to the vegetable kii dom) in the mineral leucite (1797). He made many analyses of ancient metal objects and glazes. ... 

The alum deposits on the island of Ischia outside Napoli were worked in the 12 century ad, but new applications for alum, such as for instance in the taiming of leather, increased demand so much that alum had to be imported from the Middle East Roman alum workers were active in Syria, and Roman merchants took care of the deliveries to their home provinces. However, everything was changed by Turkish expansion in the 15 century. The Romans had to return home not only to unemployment but also to the task of finding new domestic deposits of alum. In a barren mountain district at Tolfa near Rome they found the same type of vegetation that they... 

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