The term 'coating produced by oxidation' can be summarized by the word PATINA, which is a 6-letter word. PATINA is a thin layer of corrosion or discoloration that forms on the surface of metal, stone, or other materials over time due to oxidation. It is often seen as a desirable effect, as it can give an object a unique and attractive appearance. PATINA is also used to refer to the aging of a person's skin, giving them a more mature and distinguished look.