A light-weight portable X-ray spectrograph is described in some detail. The analyzing head, weighing only 18 lb, contains a goniometer, ratemeter, and Geiger counter detector. It also contains a special window-type X-ray tube with a gold target which has been developed specifically for this spectrograph, and which provides a very high efficiency of excitation of the sample. An associated power supply contains an rf source providing 40 kv at 60 μa together with the necessary voltages for the rectifier filaments, the X-ray filament, and the Geiger counter voltage. It will detect wavelengths from atomic number 23, vanadium, to atomic number 50, tin, and then using the L series from atomic number 58, cerium, to atomic number 92, uranium. Sensitivity and some applications are discussed.