ABSTRACT
The concept of weathering is relatively simple. Minerals, particularly minerals formed at high temperatures and pressures in the earth’s interior, are unstable in contact with dilute waters at the earth’s surface and tend to dissolve or transform into minerals that are more stable there. Weathering is a general term for this transformation, including the physical and chemical breakdown of the primary rock, and the accumulation of secondary products as soil. Congruent dissolution means that the entire solid dissolves, leaving no secondary solid phase. One implication of these differences is that weathering should be highly selective. If a rock contains several minerals, they will not all dissolve at the same rate. As chemical reactions approach equilibrium, the rate of the back reaction, here reprecipitation of the original solid phase, becomes finite.
