Results from the PCA applied over the spectral parameters: s, s2, s2 − s3, and s3 − s4. The upper panel shows the first three components of the PCA. These loading values (elements of the eigenvectors) are used to weight each parameter when calculating principal component scores. In the lower panel, we show the principal component space of PC2 vs. PC1. The grey hatch represents the density distribution of the 1290 Gaia asteroids that have good quality data between 0.418 and 0.902 µm. Those classified by Tholen are overplotted with color markers. Crosses correspond to the median for each taxonomy and the size of the error bars is the interquartile range.