In order to measure Fe-silicates precipitated under geological disposal conditions, a static leaching test has been conducted of simulated vitrified waste in 0.01 M FeCl$_{2}$ solution with a surface area to volume ratio = 10 m$^{-1}$ at 90$^{\circ}$C under a N$_{2(g)}$ atmosphere. Obtained results indicate that Fe bearing minerals change from green rust to Fe-rich serpentine over time. Such mineral transitions are important as they may have an effect on the alteration behavior of glasses used for geological disposal of HLW.