The rock in the picture is dark green in color and shows a psilotic texture. The surface of the bedrock was oxidized. It shows no magnetism with a bar magnet.
It looks like a conglomerate made up of chert nodules that may have developed the zonal nature of the grains after sedimentation, during diagenesis. The zonal nature may be just a colour change or a colour change associated with some recrystallization?