A device for performing both elemental and structural analysis of a crystalline sample, comprising a polychromatic x-ray source (11); a mounting means (15) for mounting the sample so that it is illuminated with x-rays; one or more fluorescence channels (17), able to select x-rays of a particular wavelength and energy and having means (20) for detecting said selected x-ray; a diffraction channel (28) able to select a characteristic x-ray wavelength at said source (11) following diffraction of the x-rays by said sample (14) and having means (33) for detecting a selected characteristic x-ray ; and an actuating means (32) for controlling arcuate movement of said diffraction channel (28) relative to said sample (14) so as to detect x-rays leaving the sample at different diffraction angles.