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Rocks are the primary source of all plant nutrients, except nitrogen. These nutrients are bound into a variety of crystalline structures (minerals).   Minerals are either formed during rock formation from magma (primary mineral) or formed during soil formation (secondary minerals).   Secondary minerals are formed when the local soil solution is saturated in respect to that mineral. In contrast to secondary minerals, primary minerals are formed in the earth mantle at high temperature and pressure.   At the earth surface these minerals may be thermodynamically unstable.   Here, in interaction with water, they either unstable, and will eventually  dissolve completely (congruent dissolution) or dissolve partly, leaving a solid residue like clay minerals (incongruent dissolution). completely.  This dissolution process is extremely slow for most minerals. It has been estimated that it takes more than 30 million years to dissolve a 1 mm diameter quartz grain under natural soil conditions \citep{Lasaga_1984}.   Nonetheless, soil mineral weathering provides an essential input of plant nutrients into ecosystems, avoiding or delaying nutrient limitations \citep{chadwick_changing_1999}.