In this paper, a white-light spectral interferometric technique is described which is employed for a direct measurement of the group refractive index dispersion for the ordinary and extraordinary waves in a quartz crystal over the wavelength range from 500 to 830 nm. This technique utilizes a dispersive Michelson interferometer with the quartz crystal of known thickness to record a spectral interferograms and to measure the equalization wavelength as a function of the displacement of the interferometer mirror. The displacement is measured from the reference position, which corresponds to a balanced nondispersive interferometer. The measured dispersion characteristics are in good agreement with theory. We also determined precisely the thickness of the crystal from the slope of linear dependence of the measured mirror displacement on the group refractive index given by the dispersion relation.