A bstract A rapid and sensitive method for the quantitative determination of the crystalline constituents in kaolin‐flint‐feldspar blends has been developed with the Geiger‐counter X‐ray spectrometer. Two variations of this method were the use of (1) a powdered sample with a reference‐material addition and (2) a polished normal body surface. The powdered‐sample technique with a reference‐material addition showed the greater accuracy and consistency of results. The polished‐surface technique was slightly less accurate, but the preparation and nature of the test specimen make it very adaptable to control methods. With this technique the complete preparation and testing of the fired surface can be carried out in approximately 10 minutes. Standardization curves for the X‐ray spectrometer technique were used to obtain quantitative information concerning the crystalline constituents in the following blends: (1) kaolin‐flint, (2) kaolin‐feldspar, (3) flint‐feldspar, and (4) kaolin‐flint‐feldspar, as well as with additions of 1.2 and 2.8% lime and magnesia, and direct substitution of nepheline syenite for feldspar. Pressed 1 1/2‐in. pellets of each body were subjected to 3‐ and 12‐hour soaking periods at 1200° and 1400°C. Quartz, mullite, cristobalite, and wollastonite were identified as the crystalline constituents in the kaolin, flint, and feldspar blends studied. Quantitative X‐ray information concerning the reduction of the free‐quartz content, formation of cristobalite and mullite, and the amount of the total crystalline content was used to determine the effects of variations in composition and heat‐treatment for the different blends.
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Tuttle et al. (1949) studied this question.