Grains of quartz and potassium-rich feldspar have been mixed in known ratios to produce samples of known mineralogical composition, analogous to those found in natural sedimentary deposits. The variation of the green light stimulated luminescence (GLSL), as a function of sample temperature, was measured for each of these mixtures in order to attempt to isolate a luminescence signal that originates specifically from just one of the components. As the sample is heated from room temperature to 450 degrees C, thermal quenching reduces the signal from the quartz component to near zero, while that from the feldspar component is enhanced. A simple ratio of the GLSL signal at 50 degrees C to that at 300 degrees C was found to provide a useful indicator of the mixing ratio. Further work will be required to characterize the behaviour of other feldspars and to develop this method so that it can be applied to real geological samples.