A recent study of difference in surface etching rates of the+xand-xplanes ofx-cut synthetic quartz has led to a more detailed understandings of the results in our previous paper, ‘Fission Fragment Registration in Synthetic Quartz'.1Considering that the difference must be due to the anisotropy of the etching rate, a general treatment of the process in which tracks are developed with an anisotropic bulk etching rate is obtained. The results are applied to fission fragment tracks inx-cut synthetic quartz plates.