Abstract Quantitative chemical analysis of individual particles from three commercial willemite fluorescent lamp powders (Zn 2SiO 4:Mn) has been made using an electron microprobe. A simple interference type spectrometer attachment and photomultiplier readout also allowed simultaneous recording of cathodoluminescence spectra of individual particles. There is significant grain-to-grain variation in the Zn/Mn and Zn/Si ratios calibrated against single-crystal material. In addition to the usual green particles, occasional orange and blue luminescing particles are observed in all the samples studied. Spectra of orange particles, which had higher concentrations of Mn, show two broad bands with peaks around 5300 Å and 5900 Å. Comparison with single crystals, artificially doped with Mn, suggest that the orange particles have a second phase, with tephroite structure, present along with willemite phase. Mn 2+ in tephroite is six-fold coordinated, thus luminescence emission from this phase would be in the red region in comparison to Mn 2+ in the willemite structure where it is four-fold coordinated.