In this work, the Scanning Reference Electrode Technique (SRET) was used to visualise the pyrite corrosion by atmospheric oxygen and its inhibition by a thymol derivative. SRET has the advantage over the potentiostatic and galvanostatic techniques of enabling in situ operation without imposing any potential or current to the sample under study. SRET revealed that the inhibiting effect is effective only if the sample is oxidised beforehand. It also revealed that pyrite corrosion by oxygen is a localised process whereas that by Fe(III) is not local, thus the oxidation of pyrite by atmospheric oxygen is not only due to the oxidative role of Fe(III). Adsorption of oxygen plays probably a determining role. Studies are now carried on to evidence the intervention of galvanic processes or catalysis phenomena occurring during the corrosion of natural conducting minerals and industrial wastes. Their aim is to better understand the mechanisms and to propose remediation processes.