The objective of this project is to develop an automated procedure, to be implemented in an IBAS image analyzer, to determine size, shape and degree of liberation of pyrite particles in a coal matrix. This procedure is to work in real time conditions and with minimal intervention from the operator. Our approach is to create from the original microscopic image a three level image with the following components: epoxy, coal materials and pyrite to simplify the calculations. Enhancing the original image by histogram scaling and median filtering, we segment it and form the three level image. After the boundaries of the pyrite particles are defined, we mask the surroundings of the particle to estimate the degree of liberation. The percentage of epoxy included in the mask is defined as the degree of liberation of the particle. Size and shape factor values are simultaneously calculated for each of the analyzed particles. These particles are classified according to their maximum diameter, shape factor and degree of liberation by the program. 6 refs., 18 figs.