I have always been interested in geology and wondered about how unique structures of materials behave in different circumstances. I stumbled upon Olivine, the magnesium iron silicate, and heard that it contained water in them, and wanted to know how the water is held within the silicate. If there is water in them, is there any way we can extract that water from within it? Just curious.
This would seem unlikely to me as the standard exposed weathering process of Olivine involves large amounts of water (per the reaction Mg2SiO4 + 4CO2 + 4H2O→2Mg2+ + 4HCO3‒ + H4SiO40) so it would be intrinsically unstable.
In a closed environment with no excess water the reaction would be
2Mg2SiO4 + 1CO2 + 2H2O → Mg3Si2O5(OH)4 + MgCO32Mg2SiO4 + 1CO2 + 2H2O → Mg3Si2O5OH4 + MgCO3 (the products being serpentine and magnesite).
Both reactions are exothermic and are CO2 negative - hence the suggestion of green fuel use for open cast extraction of olivine.
Dear Geshanth Krishnapillai: olivine contains no water, and all geologists know how easily it is altered, in hydrated conditions, to serpentine. But, it has been found that its high pressure polymorph, ringowwodite, has a spinel-type structure where some oxygens can be protonized, that is O2- becomes (OH)-, and so the mineral has about 1,5 % H2O: the deep blue color of ringwoodite in an ultra-deep diamond found in placers at Juina, Mato Grosso, Brasil, some years ago, is suggestive of its water content... Surely, extracting this structural water from ringwoodite needs very high temperatures, so even in the mantle transition zone, ringwoodite is stable and releases no water. Also, the amount of water virtually present in the transition zone has been compared to twice or thrice the total volume of ocean water, but this is combined, structural, water, no free molecular H2O.
Regards, Sebastian.
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