Fig. 4

Electrical conductivity of nominally “dry” olivine with different FeO (Mg#) content. Results shown as “truly dry” are those at room pressure (Constable et al. 1992; Hirsch et al. 1993) and at high pressure by (Dai and Karato 2014c) (shown by solid symbols and solid lines) where the water content of the sample was measured and shown to be small (less than 10 ppm wt). Results shown by “dry?” (Cemič et al. 1980; Omura et al. 1989; Yoshino et al. 2012) are the results at high pressures but the water content of their samples was not measured. The results from these high-pressure studies show much higher electrical conductivity than those of truly dry samples. The most likely reason is the presence of some water (hydrogen) in their samples. OKK: Omura et al. (1989). YMSK: Yoshino et al. (2012). CWH: Cemič et al. (1980). HSD: Hirsch et al. (1993). WMXK: Wang et al. (2006)