In the paper a simple spectral unit designed for excitation and registration of luminescence spectra of natural objects is described. The unit is composed of two basic systems: an excitation system and a registration system. Either x-ray or laser emission can be used for luminescence excitation. The registration system is based on lattice monochromator. The studied object is placed directly at the monochromator entrance slit. Two lead plates are located inside the monochromator case. They protect photodetector that is located behind the monochromator exit slit from x-ray radiation. When emission is decomposed by the diffraction grating, spectrum aliasing occurs, which can be eliminated using optical filters. The diffraction grating rotation is controlled by a computer. Manual control of the rotation angle is also provided. The PMT signal, amplified by dc amplifier, goes to analog-digital converter (ADC). Digitized ADC signal goes to COM port of the computer. Spectrum projection is displayed on the screen and can be recorded to computer’s memory. Switching of analog devises to the dc amplifier output is provided. Examples of processing of the experimental results, obtained using the abovementioned unit, are presented in the paper.