Figure 3
(a) Typical ash particles from sample VE, generated by vulcanian activity at Santiaguito. Note the blocky, dense particle shapes and the lack of vesicles. pl = plagioclase, px = pyroxene, gm = groundmass (glass and microlites) hbl = amphibole (hornblende). (b) Blocky ash particle from sample DC showing partial vesicularity in some particles, suggesting heterogeneous bubble textures. Note in both samples the lack of concavities that would be associated with fracture propagation between bubbles, commonly used to indicate magmatic fragmentation.
