**1. Introduction**

Conservation science helps preserve the memory of monuments which have been shown to be in such a declining state of neglect and decay that time is running out. Monuments that very probably cannot be restored as part of a conservation project risk disappearing without a trace. An analytical campaign of what is still possible to characterize can therefore reveal the materials, artistic techniques, decorations to future memory of a disappearing beauty. The church of Santo Stefano in Selva (Cerignale) (Figure 1), in the Apennines of Piacenza (central Italy), is in a declining state of neglect and decay. Given its location in a remote area, with no tourism, it is not a high priority for the national heritage. The local community pressed for an analytical campaign on the fragments of the few surviving paintings, in order to preserve their memory.

The area between the Po Valley and the Ligurian Sea was once much travelled, and there were also several historical pilgrimages, along important trade ridgeways, such as the salt routes, which involved the exchange of local goods. One of these routes, the "Strada del Cifalco", followed the natural path of the Trebbia Valley along the ridge between the Aveto and Trebbia rivers, connecting the north of what today is Liguria with Piacenza. It is thus not surprising that the Apennines, the mountainous system of this area, are rich in artistic testimonies, which unfortunately were neglected during the depopulation after

**Citation:** Rampazzi, L.; Corti, C.; Geminiani, L.; Recchia, S. Unexpected Findings in 16th Century Wall Paintings: Identification of Aragonite and Unusual Pigments. *Heritage* **2021**, *4*, 2431–2448. https://doi.org/ 10.3390/heritage4030137

Academic Editor: Diego Tamburini

Received: 30 August 2021 Accepted: 12 September 2021 Published: 15 September 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

the Second World War. This artistic history can be seen in the municipality of Cerignale too: the village of Ponte Organasco, with its medieval layout and many tower houses; the medieval castle of Cariseto, which hosted Emperor Frederick Barbarossa; and the church of Santo Stefano in Selva. The building is located in an area which was once a point of transit and rest for the muleteers travelling between the Trebbia valley and the Aveto valley, on their way to Liguria [1].

**Figure 1.** The remains of wall paintings in the church of S. Stefano.

Documentation on the history of the paintings is scarce. The building is listed in a church register which records the churches that in 1523 sent financial dues to the Papal State. The ruins still reveal the elaborate construction technique adopted to simulate a certain opulence, such as the vaulted ceiling, which looks like it is made of stone, but is actually a wooden structure with the intrados made of reeds covered with painted plaster. The facade of the single-nave church is relatively intact, and recalls the classical Greek temple structure. The lesenes support the very elaborate trabeation and triangular tympanum. Three transverse round arches have also remained intact. No records of the wall paintings have been found in the archives. We can thus only assume that the first cycle of paintings dates back to the construction of the building in the 16th century.

The church has almost completely lost the internal wall paintings (Figure 1). The decay originated from the partial settlement of the ground, around the middle of the last century, and more recently from a bolt of lightning that hit the stone bell tower causing a fire that almost completely destroyed the roof.

The present work reports the analytical campaign conducted on fragments from the few wall paintings still in place. The samples were analyzed with optical microscopy and scanning electron microscopy equipped with an energy-dispersive spectrometer, also on polished cross sections, and with X-ray diffraction and infrared spectroscopy on powders. The analyses obtained important information on the pictorial materials, pigments and

binders used for the decoration of the walls. Traditional and unusual pigments were revealed together with the widespread use of aragonite probably from shells utilized as a building material, which, to the best of our knowledge, has never before been found in 16th century wall paintings.

We believe that the results could contribute to maintain the memory of the history of the church and help support a material study as part of future conservation work.
