Iron hydroxide is a chemical compound composed of iron and hydroxide ions. It typically appears as a brownish or yellowish solid and is often found in nature as a mineral. Iron hydroxide can form through the reaction of iron salts with alkaline solutions, and it plays a role in various environmental processes, such as the natural filtration of water. In addition to its natural occurrence, iron hydroxide is used in various industrial applications, including water treatment and as a pigment in paints. It is also a key component in the production of iron oxide and can be involved in the formation of rust when iron is exposed to moisture and oxygen.