gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1963.033.261.09 Monochromator or Graded Spectrum Filter? Holgate Norman M.Sc., Ph.D. University of Glasgow 6 1963 33 261 512 516 Copyright © 1963, The Mineralogical Society 1963 Summary

The suitability of monochromators for visual applications in petrographic mineralogy is discussed, and a new and inexpensive instrument employing a graded interference filter is described.