  We performed low temperature scanning tunneling microscopy (STM) and
spectroscopy (STS) studies on the electronic properties of (R3xR3)R30{\deg}
phase of silicene on Ag(111) surface. We found the existence of Dirac Fermion
chirality through the observation of -1.5 and -1.0 power law decay of
quasiparticle interference (QPI) patterns. Moreover, in contrast to the
trigonal warping of Dirac cone in graphene, we found that the Dirac cone of
silicene is hexagonally warped, which is further confirmed by density
functional calculations and explained by the unique superstructure of silicene.
Our results demonstrate that the (R3xR3)R30{\deg} phase is an ideal system to
investigate the unique Dirac Fermion properties of silicene.
