FeCl3 is iron (III) chloride using the International Union of Pure and Applied Chemistry's nomenclature. Under older systems, it is also known as iron chloride or ferrous chloride. In nature, FeCl3 is the mineral molysite. Another form of ferrous chloride is FeCl2, which the IUPAC distinguishes using the name iron (II) chloride.
Iron (III) chloride is a dark green crystal when the viewer sees it using reflected light. However, if one views the crystals with the light source behind them, they appear purple-red. FeCL3 crystals have a strong affinity for water and absorb large amounts from the atmosphere to form a hydrated iron (III) chloride mist.
FeCl3 helps in water and sewage treatment. In solution, it forms iron (III) hydroxide which is useful in removing suspended materials from the water. In the electronics industry, ferrous chloride etches copper in the production of printed circuit boards. Coin collectors use iron (III) chloride to enhance dates on coins that are difficult to read. Swordsmiths and knife craftsmen use the chemical to stain blades in order to see imperfections. Its water affinity makes it an excellent desiccant to keep other materials dry. Veterinarians use FeCl3 to stop bleeding of animal claws they clip too close. Potters use Iron (III) chloride in Raku firing of their wares to produce an orange color due to the presence of iron.