Some boron minerals exhibit decrepitation phenomena at temperatures near their decomposition.The decrepitation properties of two typical boron minerals, colemanite and ulexite have been studied. The reaction temperature and reaction time have been optimized for both minerals. The results reveal that while colemanite undergoes decrepitation, ulexite shows no sign of significant fragmentation upon heating. The kinetics and fragmentation data obtained as a function of particle size indicate that colemanite produces a fragmentation pattern similar to that of minerals ground in ball mills.