Amber features. A. Forms and aspects of the collected amber grains, some having kept the characteristics of the original resin drops; note the abundance of opaque grains with earthy colours. B–E. Sections of grains in thin sections showing various situations of more or less opaque grains. F. Cracked external surface of a grain under SEM. G. Stack of resin flows within a grain. H. Opaque grains marked by dense filamentous networks. I. Opaque grain containing many bubbles and colonization by filamentous networks.