The importance of Q, and the factors that influence it, are discussed in chapter 3.  The Q of a resonator is due to a combination of factors, one of which is the quartz material.  The material can limit a resonator’s Q, but the contribution of the material cannot be determined from measuring the Q of a resonator.
	Infrared absorption by the quartz material used to make a resonator correlates well with the maximum Q achievable with that resonator, at a particular frequency; 5 MHz is the standard frequency used for correlations.  The figure above shows the transmission spectra of a 20 mm thick sample, with the IR incident along two perpendicular directions, X and Z.
	“Infrared Q” measurements, per EIA Standard 477-1, are routinely used by quartz growers and users as an indicator of quartz quality (see next page).
	J. C. Brice and A. M. Cole, "The Characterization of Synthetic Quartz by Using Infrared Absorption," Proc. 32nd Annual Symposium on Frequency Control, pp. 1-10, 1978.
	B. Sawyer, "Quality Indications From Infrared Absorption Measurements on Cultured Quartz," IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. UFFC-34, No. 5, pp. 558-565, September 1987.
	D. M. Dodd and D. B. Fraser, “Infra-red Studies of the Variation of H-bonded OH in Synthetic a-Quartz,” J. Phys. Chem. Solids, vol. 26, pp. 673-686, 1965.