It is possible with the aid of a transmission electron microscope fitted with suitable X-ray analytical equipment, to identify submicroscopic particles of the various asbestos minerals. Identification of particles should depend upon the production of accurate chemical data and not upon spectrum morphology. Suitable pure mineral powders of known chemistry can be used as standards to calibrate equipment and the calibration used to obtain the chemistry of unknown particles for a positive identification. The transmission E.M. fitted with energy dispersive X-ray analytical equipment is more versatile than other combinations of electron optical machines and X-ray analytical equipment. This is due to the more versatile operating characteristics of the transmission E.M. and the ability to display the X-ray spectra obtained from a particle with an energy dispersive analysis system, thus showing the presence of all the major elements with higher atomic numbers than sodium 11.