Deciphering the tectonic-geodynamic context of the gem-quality “noble serpentine” deposit formation combining microstructural, chemical and micro-Raman analyses in Palaeozoic olivine-bearing marbles and serpentine-hosting rocks (Pizzo Tremogge, Margna unit – Austroalpine, Val Malenco – Central Alps, Italy)

•Full characterization of noble serpentine deposits in Palaeozoic olivine-bearing marbles.•Combined optical microscopy, X-ray powder diffraction, EMPA and micro-Raman spectroscopy investigation of serpentine.•Reconstruction of the geological evolution of the noble serpentine.•Three serpentine species detected by XRPD and Raman analyses.•Geological evolution of serpentine in specific geodynamic settings.•Rock-fluid interaction through in extensional and convergent tectonics.