Routine bulk quantitative analysis of rocks and minerals presents unique problems. Many of the analytical techniques currently used for this purpose require extensive sample preparation involving dissolution of the material in question. This is unsatisfactory since it potentially introduces errors resulting from additional sample handling and preferential dissolution of some analytes. Glow discharge mass spectrometry (GDMD) utilizing a direct current discharge source overcomes the problem of sample preparation because it a direct solid sampling technique. There are however, no commercially available GDMS instruments which can analyze insulating samples such as geological materials without first mixing them with a conducting binder. This practice is undesirable since it reduces the sensitivity of the measurement, and introduces potential spectral interferences. Using a GDMS instrument employing an rf discharge source provides the analyst with the means to directly analyze nonconducting samples with little or no sample preparation, and minimal matrix dependency.