## 3 Methodology
### Material Characterization  
To obtain a precise characterization of the rock specimens and to evaluate the changes after SC CO\({}_{2}\) exposure, in mineralogy, texture and chemistry, a set of complementary analytical techniques was repeatedly applied. Petrography on thin-sections, by optical microscopy (OM), was performed by a Leica bright-field microscope (LEICA DM 2500P, Wetzlar, Germany). The X-ray powder and in situ diffractograms were produced using a Bruker AXS-D8 Advance (Bruker Corp., Billerica, MA, USA), with Cu-K\(\alpha\) radiation (\(\lambda\) = 0.1540598 nm), under the following conditions: scanning between 3\({}^{\circ}\) and 75\({}^{\circ}\) (20), scanning velocity of 0.05\({}^{\circ}\) 20/s, accelerating voltage of 40 kV, and current of 40 mA. In order to evaluate the mineralogical composition of the specimen surface, in situ grazing incidence geometry experiments were conducted, with incidence of 1.5\({}^{\circ}\) and 20 scanning from 8 to 60\({}^{\circ}\). A Hitachi S-3700N SEM (Hitachi High Technologies, Berlin, Germany), coupled with a Bruker XFlash 5010 SDD detector (Bruker Corp, Billerica, MA, USA), was used for the surface sample chemical analysis. The analysis was performed under a low vacuum at 40 Pa, with a current of 20 kV. An infrared spectrometer Bruker Hyperion 3000 equipped with a single-point MCT detector cooled with liquid nitrogen and a 20 \(\times\) ATR objective with a Ge crystal of 80 \(\upmu\)m diameter was used. An infrared spectrometer Bruker Hyperion 3000 equipped with a single-point MCT detector cooled with liquid nitrogen and a 20 \(\times\) an attenuated total reflectance (ATR) objective with a Ge crystalof 100 \(\upmu\)m diameter was used. The infrared spectra were acquired with a spectral resolution of 4 cm\({}^{-1}\), 32 scans, in the 4000-650 cm\({}^{-1}\) region. In order to ensure the representativeness of the data, each cube was analysed in nine different spots, screening the most exposed surface, and each spot was analysed three times. The whole-rock geochemistry analysis was provided by XRF, which allows for the quantification of major oxides (SiO\({}_{2}\), TiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), Na\({}_{2}\)O, K\({}_{2}\)O, CaO, MgO, MnO, FeO, P\({}_{2}\)O\({}_{5}\)), sulfur and some minor elements (Rb, Sr, Y, Zr, Nb, Th, Cr, Co, Ni, Cu, Zn, Ga, As, Pb, Sn, V, U, Cl). Analyses were performed with an S2 Puma energy-dispersive X-ray spectrometer (Bruker), using a methodology similar to that adopted by [43]. A description of the standard reference materials (SRM) utilized in the calibration method can be found elsewhere [44]. After the determination of loss on ignition (LOI), samples were fused on a [PERSON] heating chamber, using a flux (Li-tetraborate) to prepare fused beads (ratio sample/flux = 1/10). The software utilized for acquisition and data processing was Spectra Elements 2.0, which reported the final oxide/element concentrations and the instrumental statistical error (Stat. error) associated to the measurement. OM, XRD, XRF, FTIR and SEM-EDS analyses were performed at HERCULES Laboratory (University of Evora, Portugal). Linear roughness was measured by a homemade microprofilometer consisting of 55 parallel needles put in contact. The spacing between the needles' center-line is 500 \(\upmu\)m for a total measurable length of 3.5 mm. After the profile measure, a photo of the needles' position was taken. Profiles of the samples were detected by drawing a line joining all the extremities of the needles, with the help of Adobe Photoshop CC 2018. The profile line in JPG format was uploaded on online software (WebPlotDigitizer, [[https://apps.automeris.io/wpd/](https://apps.automeris.io/wpd/)]([https://apps.automeris.io/wpd/](https://apps.automeris.io/wpd/))) that allowed us to identify the X and Y values of the line according to the pixels composing the JPG photo. Pixel values were later converted to microns according to a scale.