## 2 Materials and Methods
### The Determination of Mineralogical Composition  
To determine the mineralogical composition, 12 rock samples were collected from the walls of the rupestrian church. The collection sites were distributed in such a way as to cover the entire interior of the structure (Figure 3c). The process was non-invasive for the monument, considering that only already detached samples were taken; this was important because there was no need to intervene to detach the rock. Furthermore, only the surface part of the detachment was used for the analyses.  
XRD and Raman spectra (RS) analyses were performed on the 12 samples to determine the types of minerals. XRD is a valuable method for studying crystalline phases contained in rocks, and the structural analysis of the investigated sample is also corroborated with the other applied experimental methods. The XRD analyses were performed at room temperature using a Rigaku SmartLab multipurpose diffractometer, using Cu K\(\alpha_{1}\) radiation (\(\lambda\) = 1.54056A) equipped with a 9 kW rotating anode. SmartLab Guidance (v.2) software was used to acquire the experimental data. The sample was ground to a fine, homogeneous powder using an agate pestle and mortar and mounted in a sample holder. The measurement was performed in the 5-90\({}^{\circ}\) range in steps of 0.01\({}^{\circ}\). Observation on thin sections was conducted using transmitted light polarized microscopy (BX51 Olympus, Tokyo, Japan), equipped with UMPLanFl objective lenses (5\(\times\), 10\(\times\), and 20\(\times\)). A circular cross-polarized filter (\(\lambda\) = 137 nm) was used to quantify the texture (i.e., reduction of minerals extinction and intensity of the interference colors).  
RS were obtained at room temperature with a Raman Spectrograph Horiba Jobin-Yvon RPA-HE 532 with a multichannel air-cooled (\(-\)70 \({}^{\circ}\)C) charge-coupled device (CCD) detector, using a Nd-Yag laser 532 nm excitation source and a nominal power of 100 mW. Spectra were obtained in the spectral range between 210 and 3400 cm\({}^{-1}\) with a spectral resolution of 3 cm\({}^{-1}\). The Raman system includes a Superhead fiber optic Raman probe for non-contact measurements with a 50\(\times\) LWD Olympus objective lens, numerical aperture (NA) = 0.50, working distance (WD) = 10.6 mm, and FIB50/10M optical fiber. The laser spot diameter on the sample surface was approximately 2-3 \(\upmu\)m (the minimum theoretical spot diameter is 1.3 \(\upmu\)m). Sulfur and cyclohexane were used for the calibration. Data acquisition was performed at a laser power of 1-53.6 mW on the sample's surface. Furthermore, the  
Figure 4: A diagram containing the work steps.  
laser power was gradually increased by 1% until any photochemical degradation was observed. Spectra manipulations consisted of basic data treatment, such as smoothing adjustments and peak fitting (Lorentz function).  
The use of RS to complement XRD offers the advantage of a more comprehensive characterization of samples by identifying both crystalline structures and amorphous phases, to which XRD is less sensitive. RS can detect chemical bonds and organic compounds not visible by XRD, making it useful in the analysis of biodeterioration and organic contaminants. RS also enables non-destructive analysis with minimal sample preparation, providing details of molecular structure and the possibility of mapping compositions on a microscopic scale.