What is oxidation in geology ?
Oxidation : definition
In geology, the oxidation zone designates the upper part of a metalliferous concentration, located between the surface of the ground and the hydrostatic level. In this zone the primary ore, generally composed of sulphides, undergoes strong alteration under the action of meteoric agents (water, frost, etc...) and living organisms, which results in the neoformation of oxides, hydroxides, carbonates, sulphates , arsenates, native metals, etc...
These neoformations are generally accompanied by enrichments which can themselves constitute mining deposits.
The top part of the oxidation zone very commonly has a rusty tint due to the abundance of iron oxides, which has earned it the name "gossan". Towards the bottom, the oxidation zone passes to the cementation zone, another zone of concentration of the elements dissolved in the superficial part.