Distribution of metallicity for GELDAs and non-GELDAs. The left panel presents the kernel density estimation (KDE) with an Epanechnikov kernel and a bandwidth = 0.5 both for GELDAs (solid blue line) and non-GELDAS (solid red line). The dashed black lines show the differences. The blue and red shaded areas show where GELDAs and non-GELDAs are the dominant population, respectively. We clearly see that GELDAs preferentially cluster at low metallicity, with a threshold estimated at 12 + log₁₀(O/H) = 7.60. The Kolmogorov-Smirnov test confirms that the difference is highly significant. We show predictions for the transition from stardust to ISM from some of the models (see main text for more works): Asano et al. (2013) (orange shaded area), Zhukovska (2014) (green shaded area), and Feldmann (2015) (dashed orange line). Rémy-Ruyer et al. (2014) found a larger scatter in their dust-to-gas ratio covers almost the same metallicity range: 7.2 ≲ 12 + log₁₀(O/H) ≲ 8.5. All of these metallicities are in good agreement with our estimated threshold. The middle and right panels show the rolling averages (window size = 15) of the metallicity as a function of A_FUV and log₁₀ (M_dust). Both panels confirm the difference between GELDAs (blue) and non-GELDAS (red).