 Four dihalides of cobalt ( II ) are known : cobalt ( II ) fluoride ( CoF2 , pink ) , cobalt ( II ) chloride ( CoCl2 , blue ) , cobalt ( II ) bromide ( CoBr2 , green ) , cobalt ( II ) iodide ( CoI2 , blue @-@ black ) . These halides exist in anhydrous and hydrated forms . Whereas the anhydrous dichloride is blue , the hydrate is red . 
