XRF analysis of major and minor elements in silicate rocks using fused glass discs at high dilution ratio. X-ray fluorescence (XRF) is an accurate, rapid spectroscopic technique for chemical element determinations on rock samples. The aim of this research was to evaluate a calibration method for the determination of major and minor elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe) in silicate rocks using fused glass discs with a 1:30 sample/borate dilution. The analytical method has been calibrated by using forty-two international rock standards. The accuracy appears acceptable for many mineralogical and petrographic purposes. A high dilution ratio makes possible the use of a small amount of sample (225 mg) to obtain good castings in high-melting materials. By contrast, the decrease of the analytical intensity makes not easy the determination of trace elements at the typical concentration levels of geological samples