Fig. 1
From: Combined effusive-explosive silicic volcanism straddles the multiphase viscous-to-brittle transition

Photomicrographs of obsidian from Hrafntinnuhryggur, Krafla volcano (Iceland) collected in situ toward the margins of an effusive dyke-geometry conduit17 with textural evidence for fracture formation and subsequent healing while at high temperature (marked with arrows). These images were taken by Jenny Schauroth