Mass-weighted average stellar metallicity ([M/H]_M) distribution of our samples of galaxies in voids (dashed blue line), filaments & walls (dot-dashed green line), and clusters (solid red line) for three stellar mass bins as labelled. The number of galaxies in each sample is shown in the legend. The peaks at ∼0.4 are due to the metallicity limit of the E-MILES stellar models. The distribution sharply ends at higher values (∼0.5) than the limit due to the widening by the errors.