planet

Serpentinization

The reaction between seawater and the magnesium-iron olivine of the mantle, which gives off heat and produces serpentine minerals, magnetite, and a large amount of dissolved hydrogen. It is the engine behind alkaline hydrothermal vents: it supplies its own heat, its own reductant, and makes the outflowing fluid strongly alkaline — the three conditions a vent origin of life needs, with no biology involved at all.