Which chemical element of the periodic table is the most corrosion-resistant of all metals?

Corrosion is a natural process for gradual destruction of metals by chemical or electrochemical reaction with their environment. Example: Rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. The type of damage produces metal oxide(s) or salt(s) with distinctive orange colouration. The volcanic gases have accelerated the extensive corrosion of abandoned mining machinery, redering it almost unrecognizable.

Iridium is a chemical element with symbol Ir and atomic number 77. Iridium is the most corrosion-resistant metal of all metals in the periodic table. It is the only metal to maintain good mechanical properties in air at temperatures above 1,600 deg C (2,910 deg F). It has melting point 2446 deg C (4435 deg F) and boiling point 4130 deg C (7466 deg F). Iridium is not attacked by almost any acid, aqua regia (mixture of nitric acid and hydrochloric acid in the ratio of 1:3), molten metals, or silicates at high temperatures. It can, however be attacked by some molten salts such as sodium cyanide and potassium cyanide, as well as oxygen and particularly fluorine at higher temperatures. Smithson Tennet (30 November 1761- 22 February 1815) was an English chemist. He is best known for the discovery of Iridium who named 'iridium' after the Greek goddess of Iris.