During September and October 2009 the University of Siena’s School of Medieval Archaeology carried out a second excavation campaign on the site of Monteleo, extending the 2008 excavation area. By the end of the season two of the four kilns were completely excavated, whilst a third was only partially so. The archaeological data provided information regarding the structures’ function and chronology.

The first of the two excavated structures (Kiln 1) was certainly for lime production. The kiln, whose internal stratigraphy was completely removed, had a maximum diameter of 3.58 m, interior diameter of 2.50 m and was 3.18 m deep. Inside the kiln, deposits containing charcoal and ash were bordered by a series of simple structures, defined as “spallette”, thought to have served as an aid to the stacking of the materials to be fired.

The excavation of kiln 2, overall depth 2.90 m, foresaw the removal of the rubble layers resulting from the structure’s abandonment, below which were levels of ash, charcoal and stones. These layers were cut by the construction of a brick-built offset, already uncovered by the 2008 excavations, at 1.66 m below ground level. The presence of such a structural element, which did not show any significant alterations caused by exposure to high temperatures provided important evidence for the function of this structure. In fact, this type of element is not attested in lime-kilns, whilst it would be more in keeping with the leaching process, during which large metal cauldrons were inserted into the furnaces, supported on particular housings. This hypothesis, also supported by a comparison with other known structures, would also explain the lack of alteration in the bricks forming the offset, as the temperatures reached by leaching kilns are much lower than those necessary for the calcination process, which occurred at between 500° and 600°.
The excavation was extended to the third kiln structure, which was dug to a depth of 2.15 m.

Inside the kiln a number of pottery vessels, some intact, came to light. They had been leant on the brick offset in a late phase when the structure was no longer used as a kiln. The assemblage was quite rich and comprised closed forms (slipped flasks, glazed cooking pots) and open forms (large marbled plates, enamelled bowls, glazed casseroles), productions that were circulating in the area between the 16th-17th century. This pottery dated the end of the kiln 3’s productive phase to during the 15th century.

The new excavation data, in particular that regarding the diverse kiln typologies, together with the dating from the pottery found in kiln 3, confirms what was hypothesised in the previous year. It also showed that these were not 18th century late grand-ducal structures, as described in the well known text written by Targioni Tozzetti, dating to 1754, rather these structures were what remained of the earlier alum mine founded by Rinaldo Tolomei at the end of the 15th century.