iron oxide crossword clue

 The answer to the crossword clue "iron oxide" is RUST (5 letters). Rust is a reddish-brown coating that forms on iron and steel when they are exposed to oxygen and water. It is a form of oxidation, which is a chemical reaction that occurs when a metal combines with oxygen.

Rust can cause iron and steel to weaken and eventually break. It can also be unsightly and can reduce the value of an object.

There are a number of ways to prevent rust, including painting or coating the metal with a rust-resistant substance, keeping the metal dry, and using rust-resistant nails and screws.

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