A two-prong rotary drill bit for engaging an earth strata material includes a drill bit body having an axis of rotation, the drill bit body having a head portion at an axial forward end and a shank portion at an axial rearward end, the head portion having two mounting arms offset from the axis of rotation of the drill bit body. The two-prong rotary drill bit also includes a cutting insert attached to each mounting arm at the axial forward end of the drill bit body. Each cutting insert includes a leading face facing in the direction of rotation, a top surface having a relief surface, a T-land surface extending between the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.