<P> Because of the widespread use and importance of iron and steel products, the prevention or slowing of rust is the basis of major economic activities in a number of specialized technologies . A brief overview of methods is presented here; for detailed coverage, see the cross-referenced articles . </P> <P> Rust is permeable to air and water, therefore the interior metallic iron beneath a rust layer continues to corrode . Rust prevention thus requires coatings that preclude rust formation . </P> <P> Stainless steel forms a passivation layer of chromium (III) oxide . Similar passivation behavior occurs with magnesium, titanium, zinc, zinc oxides, aluminium, polyaniline, and other electroactive conductive polymers . </P> <P> Special "weathering steel" alloys such as Cor - Ten rust at a much slower rate than normal, because the rust adheres to the surface of the metal in a protective layer . Designs using this material must include measures that avoid worst - case exposures, since the material still continues to rust slowly even under near - ideal conditions . </P>

What is the texture of the element iron