San Lorenzo Church in Turin– A stone exhibition of more than 3 centuries ago

The church of San Lorenzo is a ducal chapel located in one the main squares of Torino, whose costruction was due to a promises of the Duke of  Savoia Emanuele Filiberto for its safe after the San Quintino battle won in the day of San Lorenzo in 1557. The expansion works on the church actually began in 1634, but were soon interrupted by the death of Vittorio Amedeo (1637) and the resulting civil war, and only thirty years later, with the call of the mathematician Guarino Guarini, the church construction moved on to the resolution phase. For the dome he renewed schemes with a distant ancestry in Gothic and especially oriental architecture. The works for S. Lorenzo lasted a long time: the church was completed by 1679 and consecrated later only after the architect also designed the main altar.

The innovation of the Church of San Lorenzo is certainly the rich variety of decorative stones that we can admire inside and above all the different methods of use that Guarini managed to implement, changing the intended use, and introducing other particular stones which were, at the time, still unknown in Italy.

The main stones used inside the church, are the different types of Frabosa marble, San Martino marble, Foresto marble, Gassino limestone (Piedmont) and Arzo marble (Switzerland) while in the seven chapels, a very large use of Verde Alpi marble, , together with the bright Giallo Reale in contrast with the two blacks, from Frabosa and Portovenere are present.. The use of a different stone for each imposing pair of columns of the various chapels was also sought after, in this regard the green Alpi, the black Portoro, the Rosso Verona but also the breccia of Seravezza, the Gialletto of Verona and the particular Sicilian Libeccio of Custonaci were used.

Furthermore, from the analysis of the different altar frontals the triumph of the charm of different polychrome marbles, assembled excellently together, in a space of limited dimensions is evident.

Verde Alpi and Giallo Reale together with Arabescato Orobico and Spanish Broccatello, are all in great contrast by the black Frabosa marble.

Petrographic knowledge is fundamental in providing the tools for the preservation of cultural heritage as it allows us to carry out recovery interventions on architectural complexes and ancient art objects, having full knowledge of the material on which we are working, being able to proceed with the restoration or a possible replacement of part of the material, preserving its history, origin and characteristics.

In San Lorenzo the enormous wealth of stones will certainly remain a treasure to be protected over time and the possibility of being able to study their history and lithological provenance remains the most interesting aspect of the work I have carried out.