Fig. 1. H₂ production from crushed granite flash heated to 30 °C, 60 °C, or 121 °C compared to Kita et al.⁷.

A H₂ production from crushed granite measured by ref. 7. (left axis) compared with this study (right axis). The data from ref. 7 were measured at 20–30 min, while our study measured the data 1 h after heating (incubation at 0 °C). The line represents a trendline for data of ref. 7. and data are accurate to 15%. Error bars for this study are the standard error of the mean (not visible). B H₂ production 1, 24 and 168 h after flash heating of granite to 30, 60 or 121 °C (0 °C incubation). Concentrations are blank corrected, and bars with squares are significantly different from the blanks (Mann-Whitney U: P < 0.05). The error bars are the standard error of the mean.