The process of metamorphism is one of change, and within the mineral assemblage and texture of a metamorphic rock is a memory of that change. The transformations are brought about by geological processes from the global plate tectonic level to the more localised scale. In view of this, recovering the memory of the change locked in metamorphic rocks helps to constrain geological processes well back into the Earth's history.

The ever increasing amount of data on crystal arrangement in igneous and metamorphic rocks, alloys and ceramics, shows that the microtextures of these materials result from sequences of crystal growth and resorption. Metallurgists have become knowledgeable in the interpretation of textures and can make or modify textures of alloys in order to obtain specifjc responses to traction, distortion, etc. The modifications in texture can be reproduced or changed as often as desired. By analogy, it is probable that the microtextures observed in rocks may result from the same processes that govern similar textures in manufactured products. <...>