The session welcomes contributions from natural, experimental, modelling and theoretical studies involving microstructures and textures in relation to rheology. It is a continuation of the successful sessions on this topic of EGU2008 and EGU2009. The aim is to discuss aspects that are still poorly understood, and new questions that have arisen regarding the measurement (by conventional and new techniques) and interpretation (applying previous and new theories) of microstructures and textures to identify deformation processes and mechanisms. We welcome contributions dealing also with the feedbacks between fluids, metamorphic reactions, and deformation. Porosity, permeability and fluid migration in ductile shear zones are important aspects that we expect to discuss. We aim to show examples integrating views from metamorphic petrology, structural geology, mineralogy and economic geology.