High Quality Content by WIKIPEDIA articles! Iron hydride describes a family of materials with the formula FeHx. These materials are viewed as compounds of Fex+ bound to the anion H-, which is called hydride. Iron hydrides are not found at normal conditions on Earth. Because these two elements are very common in the universe, their interaction has attracted much interest. Under 35,000 atmospheres of hydrogen, iron forms solid FeHx. The FeH molecule has been detected in the atmosphere of cool stars. The iron dihydride (FeH2) molecule is stable at cryogenic temperatures.