The analysis of geological samples by x-ray fluorescence analysis is complicated by matrix effects and sample variability. Diluting the sample in a suitable matrix such as lithium tetraborate and then fusing it helps to reduce problems associated with sample inhomogeneities and reduces matrix effects considerably.

Unfortunately, many of the trace elements in the sample can be diluted below their detection limits by this technique. Pressing the ground powder into a hard disk avoids this problem and is less time consuming. Matrix effects can be very serious however, but can be calculated and compensated for by fundamental parameters programs.