Fiducial t-SNE projection of the Delgado Mena et al. (2017) sample (see big panel in Fig. 1), colour-coded by chemical abundances (top three rows), spectroscopic parameters (effective temperature T _eff, surface gravity logg, microturbulence ξ, and signal-to-noise ratio logS/N; fourth row), age τ (fifth row, first panel) and space velocities (fifth row). We note that only [Fe/H] and the [X/Fe] ratios were used as input for the t-SNE run.