The effect of pressure on the optical rotatory power and dispersion has been investigated on single crystals of α-quartz over a pressure range of 3.5 kbar in the visible region of the spectrum. The optical rotatory power is found to decrease linearly with pressure with the magnitude of dρ/dP increasing with decreasing wavelengths. These results are shown to be in accordance with the pressure variation of a single-term quadratic dispersion equation.
M. B. MYERS and K. VEDAM, "Effect of Pressure on the Optical Rotatory Power and Dispersion of α-Quartz," J. Opt. Soc. Am. 56, 1741-1744 (1966)