Fig. 4
From: Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan
Photographs of scoriae shrunk by heating. a, c, e and b, d, f show the photographs and porosities of scoriae before and after heating, respectively. Initially, the muffle furnace is kept at 1150 °C. When we open the furnace to place the samples inside, the internal temperature drops. We include this recovery time in the heating time