Pressure-induced amorphization of minerals: a review
Richet, Pascal; Gillet, Philippe
European Journal of Mineralogy Volume 9 Number 5 (1997), p. 907 - 934
published: Sep 24, 1997
manuscript accepted: Mar 13, 1997
manuscript received: Apr 15, 1996
ArtNo. ESP147050905001, Price: 29.00 €
Abstract A variety of minerals transform to an amorphous material when statically compressed to a few tens of GPa. With quartz and the quartz-type forms of GeO2 and AlPO4 as examples, pressure-induced amorphization is first described with reference to differential stresses, crystalline transformations, compression mechanisms and shearing processes. Less comprehensive information is available for the amorphization of other minerals, but similar features are nevertheless observed for framework silicates, pyroxenes, olivines and hydrous silicates. The differences and similarities between amorphous substances obtained by cooling of liquids, static compression or decompression of crystals, moderate heating of high-pressure minerals at 1 atm, and shock waves are then reviewed. Finally, the thermodynamics of amorphization is discussed and the mechanistic interpretations of amorphization are presented, with special reference to elastic and dynamic instabilities and shearing processes.