## 3 Materials and Methods  
Overall, 18 ultramafic samples from the tested ophiolite complexes were selected according to EN 932-1 [64] standard and petrographically analyzed by using a combination of petrographic methods (Figure S1). The mineralogical and textural characteristics of the samples were studied in polished-thin sections in polarizing optical according to EN-932-3 [65] standard for petrographic description of aggregates, scanning electron microscopes (SEM) and by using the Rietveld method in XRD patterns of bulk samples. The bulk samples of the investigated samples were determined by powder X-Ray diffraction (XRD), using a Bruker D8 Advance diffractometer, with Ni-filtered CuK\(\alpha\) radiation. Random powder mounts were prepared by gently pressing the powder into the cavity holder. The scanning area for bulk mineralogy of the specimens covered the 20 interval 2-70\({}^{\circ}\), with a scanning angle step size of 0.015\({}^{\circ}\) and a time step of 0.1 s. The mineral phases were determined using the DIFFRACplus EVA 12\({}^{\otimes}\) software (Bruker-AXS, Madison, WI, USA) based on the ICDD Powder Diffraction File of PDF-2 2006 while the semi-quantitative analyses were performed by TOPAS 3.0 \({}^{\otimes}\) software (Rietveld method). The quantification errors (Bish and Post [66]) are estimated to be ~1% and the detection limit is 2%. The surface texture of aggregate particles was studied in secondary electron images (SEI) according to BS 812 Part 1 [67], which outlines six qualitative categories: glassy, smooth, granular, rough, crystalline, honeycomb and porous. Mineral chemistry analyses were performed using a JEOL JSM-6300 SEM equipped with energy dispersive and wavelength dispersive spectrometers and INCA software at the Laboratory of Electron Microscopy and Microanalysis, University of Patras. Operating conditions were accelerating voltage 25 kV and beam current 3.3 nA, with a 4 \(\upmu\)m beam diameter. The total counting time was 60 s and dead-time 40%. Synthetic oxides and natural minerals were used as standards for our analyses. Detection limits are ~0.1% and accuracy up to 5% was obtained.  
Major and trace elements were identified by chemical analyses at Bureau Veritas Mineral Laboratories at Vancouver (Canada) using an XRF spectrometer and a sequential spectrometer (ICP-ES). Trace elements as well as REES were identified with an inductively coupled plasma-mass spectrometry (ICP-MS). The detection limits for major and trace elements are from 0.01 wt% to 0.04 wt% and from 0.01 ppm to 10 ppm.  
The determined properties of the ultramafic rocks were the uniaxial compressive strength, the Los Angeles abrasion value, the moisture content, the total porosity and the Soundness test. The moisture content (w) was performed in accordance with the AASHTO T-255 [68] standard. Another important property influencing the mechanical performance of the aggregates is that of the total porosity (n\({}_{\text{t}}\)). This test was calculated in rocks by following the I.S.R.M 1981 [69] standard. The Los Angeles abrasion (LA) test shows the resistance of a rock to impact, abrasion, attrition and grinding (ASTM C-131 [70]--\"B\" gradation). The uniaxial compressive strength (UCS) constitutes one of the most crucial parameters in rock engineering. For this test, 6 cylindrical rock specimens with a height/diameter ratio between 2 and 3, and their diameters ranging from 51 to 54 mm (ASTM D-2938 [71]) were used. The Soundness test (S) was used for the assessment of the ability of an aggregate to its resistance in excessive volume changes as a result of changes in the physical environment (EN 1367-2 [72]).