. Toward lower temperatures, H2(aq) concentrations for pyroxenites
decrease asymptotically and remain well below those predicted
for serpentinization of peridotite (Fig. 8). It is apparent from Fig. 8 that
H2(aq) concentrations vary as a function of the orthopyroxene–olivine
mass ratio. That is, the more orthopyroxene that is present in the
protolith, the lower the overall H2(aq) generation. In contrast to
serpentinization of peridotite, serpentinization of pyroxenite does not
produce magnetite, and H2(aq) generation is controlled by the amount
of Fe+3 in the serpentine