High Quality Content by WIKIPEDIA articles! Hafnium(IV) chloride is the inorganic compound with the formula HfCl4. This colourless solid is the precursor to most hafnium organometallic compounds. It functions as a Lewis acid and catalyst for certain alkylation and isomerism reactions. Hafnium the metal center in the complex occurs in nature in small amounts associated with Zirconium minerals such as zircon, cyrtolite and baddeleyite. Zircon contains 0.05 to 2.0 percent Hafnium oxide HfO2, cyrtolite with 5.5 to 17 percent HfO2 and baddeleyite contains 1.0 to 1.8 percent HfO2.