e. Reactions (R2) and (R3) apply only to serpentinization of
olivine dominated-rocks or, if geochemical exchange is spatially limited
during serpentinization, to olivine-dominated domains within a rock.
Serpentinization of orthopyroxene-dominated rocks cannot proceed
via Reactions (R2) and (R3), since brucite is not stable in the relatively
high-silica environment of orthopyroxene and water (Fig. 1)