A method for determining mineral compositions by measurement of the mass absorption coefficient

A technique is described whereby measurement of the mass absorption coefficients of minerals can be used to give an estimation of the mineral composition. Direct measurements of $μSrKα$ on chemically analyzed plagioclases demonstrates the applicability of the method. The straight line regression so derived from 41 plagioclase samples gives the following equation: An % = 25.27 $μSrKα−164.66$, with a standard deviation of 1.61 % An.

The method can be extended to other solid solution series, such as olivine, orthopyroxene and zincblende series, and calculated values of $μSrKα$ for different members of these series are presented. By judicious selection of the wavelengths of the absorbed X-ray beam the effects of interfering elements can be reduced to a minimum.

Although the experimental work reported in this paper was done using an X-ray spectrograph, measurements of μ can be made using a diffractometer.

The advantage of this method over other indirect methods for determining mineral compositions is that the measured values of μ are directly related to the chemical compositions of the samples.