Magnesium Isotopes - Tracer for the Global Biogeochemical Cycle of Magnesium Past and Present or Archive of Alteration?

Magnesium is a major constituent in silicate and carbonate minerals, the hydrosphere and the biosphere. Magnesium is constantly cycled between these reservoirs. This review summarises some of the key motivations, successes and challenges facing the use of magnesium isotopes to construct a budget of seawater magnesium, present and past.