With a vacuum two‐crystal spectrometer the (1, −1) curves of etched quartz, etched calcite and relatively poor calcite cleavage surfaces have been studied throughout the wave‐length range 0.5 to 5 Angstroms. The widths of the curves at half maximum intensity, the percent reflection, and the coefficient of reflection have been measured. The shapes of the (1, −1) curves vary with wavelength but vary oppositely with quartz and with calcite. The study is primarily concerned with the possibilities of etched quartz as spectrometer crystals. The resolving power of x‐ray spectrometers can be increased by a factor of 2 to 4 by using quartz instead of calcite but the diminution of intensity necessarily associated with such an increase in resolving power may be impractical except for studying relatively strong characteristic radiation.