In a previous paper [J. Acoust. Soc. Am.28, 1158 (1956)], it was shown that the gravest mode of contour vibration of anisotropicthin circular plate has the circumferential order of two and is mostly equivoluminal in nature. Although the exact expression of the displacements includes Bessel functions, it can be reasonably approximated by a simple combination of trigonometric functions, which makes it possible to handle theanisotropiccase. Since the mode is the gravest, Rayleigh's principle is applied in a procedure of approximation, taking an angle of rotation and a wave number as adjusting parameters.The results are compared with experiments of quartz vibrators. Calculated frequencies show agreement better than 1% with an exact value for isotropic plates and an observed value for a rotated Y cut of quartz, which has a limited anisotropy. The accuracy decreases as the degree of anisotropy increases. For the X cut of quartz, the calculated value is 4.7% higher than an observed value.One of the significant characteristics of the mode of vibration of an anisotropic plate is the fact that the direction of maximum displacement makes a certain angle with a crystallographic axis. The calculated value of this angle agrees exactly with the observed angle for the rotated Y cut of quartz and within a few degrees for the case of the X cut of quartz.Equivalent electric circuit constants and surface patterns of piezoelectrically induced charges are also calculated and compared with experiments.