Extended Data Fig. 2: Scanning electron micrographs of volcanic particles with additional features of broken crystals and healing fractures.
From: Fracturing and healing of basaltic magmas during explosive volcanic eruptions
a-c, Ash-sized pyroclasts fringed by broken crystals, reflecting the propagation of large, clast-forming fractures and smaller ones that healed after breaking the crystals. d-f, Transitions between clast- and crystal-cutting fractures. Open fractures (d) surrounded by broken crystals with glass-filled fractures. e,f, A fracture almost dividing an entire clast, except for a narrow, viscously healed portion with vesicles and broken crystals. g, Flow banding of Fe-rich glass around broken crystals. h-j, Dispersal of crystal fragments marks post-fracture melt flow direction, with a rotational flow component (i) or shearing similar to boudinage (j). k-o, Features of broken crystals in microcrystalline groundmass are identical to those in glassy groundmass (see previous figures). Note the intermingling of the two types of groundmass (k,n), and the presence of nano-scale Fe-oxide crystals in the crystal-cutting fracture infill (o). Red boxes are enlarged in the subsequent panel.
