texture{ pigment{ radial frequency 35 
                         color_map{ [0.0 color Black]
                                    [0.4 color White]
                                    [0.6 color White]
                                    [1.0 color Black]
                                  }
                       }   
                finish { phong 1 } 
                rotate<0,0,0> scale 0.25 translate<0,0,0>
              } // end of texture -----------------------