An elemental analyzer for identifying quantities of one or more elements in a material has a container for holding a material to be analyzed, a resonant gamma ray source unit for directing resonant gamma rays into the material in the container, and at least one detector for detecting gamma rays resonantly scattered by at least one predetermined element in the material. The resonant gamma ray source unit has an outer housing of gamma ray shield and a radiological shield material, with an inner chamber and an aperture directed towards the container, a moving gamma ray generator source of predetermined materials mounted in the chamber, the materials being selected from a predetermined group of materials which emit resonant gamma rays when exposed to particles or photons, the source being directed towards said aperture, and a source of particles or photons positioned in the chamber adjacent the gamma ray generator source.