Considering the heavy use by the geological community that followed, it is not surprising that first two authors of the introductory paper in Science on the energy dispersive x-ray spectrometer applied their x-ray microanalysis skills predominantly in the geological sciences. The energy dispersive spectrometer became first commercially available at an ideal time for the geological community. During the 1960’s, mineralogists and petrographers like K. Keil, J.V.P. Long, J.C. Rucklidge, J.V. Smith, A. Albee, and A. Chodos demonstrated that electron microprobe analysis with wavelength dispersive spectrometers could provide accurate in-situ analysis of portions of individual mineral grains on a scale not readily obtainable by other techniques (e.g., 2-3 and cited refs.). The electron microprobe enabled analysis of features observed by reflected- and transmitted-light polarized optical microscopy (prime tools of the mineralogist and petrographer) and was beginning to be used routinely for the study of meteorites and terrestrial rocks and even more exotic types of specimens, like individual microparticles from sediment and airborne particulate samples.