Einsteinium(III) chloride (EsCl3) can be prepared by annealing einsteinium(III) oxide in the atmosphere of dry hydrogen chloride vapors at about 500 °C for some 20 minutes. It crystallizes upon cooling at about 425 °C into an orange solid with a hexagonal structure of UCl3 type, where einsteinium atoms are 9-fold coordinated by chlorine atoms in a tricapped trigonal prism geometry. Einsteinium(III) bromide (EsBr3) is a pale-yellow solid with a monoclinic structure of AlCl3 type, where the einsteinium atoms are octahedrally coordinated by bromine (coordination number 6).