Diagnostic analysis of Sacred Hosts from the basilica of San Francesco (Siena) through a multi-disciplinary approach

The Basilica of San Francesco hosts 233 Holy Hosts that were consecrated on occasion of the Assumption of Mary in 1730. The Hosts were stolen and abandoned without the pyx in the alms box of the Church of Santa Maria in Provenzano, where they were found. Once returned to Siena, they were not used, being kept for years to remember their miraculous retrieval and the Christian sacrament of Eucharist. A multi-disciplinary approach based on non-invasive techniques usually employed in Cultural Heritage diagnostic can be usefully used to assess the conservation state of Sacred Hosts. The performed analysis confirms the good conservation of the Sacred Hosts from biological and chemical-physical point of view, also after 284 years. Furthermore, this case study shows how the "science" can be a cross-cultural communication media to valorise religious aspects.