Pitting corrosion, or pitting, is extremely localized corrosion that leads to the creation of small holes in the material – nearly always a metal. The failures resulting from this form of corrosion can be catastrophic. With general corrosion it is easier to predict the amount of material that will be lost over time and this can be designed into the engineered structure. Pitting, like crevice corrosion can cause a catastrophic failure with very little loss of material. Pitting corrosion happens for passive materials. The classic reaction mechanism has been ascribed to Ulick Richardson Evans.