A method for the quick and reliable quantitative determination of quartz in clay by infrared spectroscopy by using the cast film technique is presented. The technique is demonstrated for two different internal standards, calcium carbonate and manganese carbonate, and is compared with a mull oil technique. The calibration curves were prepared with synthetic mixtures of standard kaolinite and quartz. Analysis of powdered samples demonstrated an absolute precision of less than 1.0% with an accuracy of less than 1.0% when using the manganese carbonate as the internal standard.
