structural:summarization
Oxidation

Within the weathering environment, chemical oxidation of a variety of metals occurs. The most commonly observed is the oxidation of Fe (iron) by oxygen and water to form Fe oxides and hydroxides such as goethite, limonite, and hematite. This gives the affected rocks a reddish-brown coloration on the surface which crumbles easily and weakens the rock. Many other metallic ores and minerals oxidize and hydrate to produce colored deposits, as does sulfur during the weathering of sulfide minerals such as chalcopyrites or CuFeS oxidizing to copper hydroxide and iron oxides.