highly significantp = 0.0003
Size metrics show highly significant differences: mean Feret diameter (U = 87, p = 0.0003, r = 0.64), median Feret diameter (U = 90, p = 0.0004, r = 0.62), and SD Feret diameter (U = 120, p = 0.0045, r = 0.50), with Los Villares exhibiting larger and more variable grain sizes.