Figure 4

(a) The average fraction of each phase in all ash particles analysed for samples VE (red bars) and DC (blue bars). Solid bars show the total phase fraction and open bars show the boundary phase fraction. Inset: Magnified view of phases with <6% area fraction, highlighted in grey. The key in the top right applies to both the main panel and the inset. (b) The ratio between phase fraction at the boundary to the total phase fraction for the six most abundant phases in samples VE (red bars) and DC (blue bars).