Final Report Summary - DELTA-MIN (Mechanisms of Mineral Replacement Reactions) The report below is also attached as a pdf file.Mechanisms of Mineral Replacement ReactionsContact Details: Delta-Min Office, Prof. Andrew Putnis, Institut fürMineralogie, Corrensstrasse 24, 48149, Münster, GermanyProject Website: www.delta-min.comThe scientific objective of the DELTA-MIN project was to significantly advance the understanding of fluid-induced mineral transformation mechanisms by exploring a wide range of diverse phenomena from a unified point of view. The project combined observations of fluid-induced replacement in natural rocks, experimental studies of mineral-fluid interaction and fundamental theory to understand dissolution, precipitation and mass transport. Observations ranged from the mega- to the nano-scale: from estimating the extent of metasomatism in rocks, to high resolution transmission electron microscopy of reaction interfaces.The methods used to achieve these objectives included:• In situ Atomic Force Microscopy to study crystal growth and dissolution mechanisms• Hydrothermal experiments in various types of reactors to study mineral replacement mechanisms• Dissolution rate studies in both flow-through and batch reactors• Field work in areas where fluid-rock interaction can be studied on an outcrop scale• Scanning and transmission electron microscopy to study reaction microstructures in both experimental and natural samplesSignificant breakthroughs were made on a number of research problems:• Atomic Force Microscopy of in situ crystal growth and dissolution mechanisms has demonstrated that background electrolytes can have a significant effect on kinetics by modifying water dynamics.• Hydrothermal experimental studies coupled with observations from natural rocks have identified replacement mechanisms and mass transport pathways.• The mechanism of leaching was unambiguously identified as a sequential process of congruent dissolution coupled with reprecipitation, in contrast to the accepted view of solid state interdiffusion.• A unified concept of fluid-induced mechanisms of metasomatism and metamorphism in natural rocks has been published.• Carbonation mechanisms of silicate rocks have been described from both experiments and studies of natural carbonated rocks.• Dissolution rates of minerals have been related to surface crystallographic orientation, providing a a more mechanism-based interpreatation of rate data.• The crucial importance of an interfacial boundary layer at the mineralfluid interface has been demonstrated experimentally, showing thatsupersaturation in the bulk fluid is not a criterion for precipitation.The overall conclusions of these results are that in multicomponent minerals fluid-mineral interactions take place by(i) a dissolution step which usually results in a supersaturation in a boundary layer at the fluid-mineral interface(ii) precipitation of a product phase which may take place within this boundary layer, and(iii) establishment of a feedback between dissolution and precipitation.This coupled process, which may be manipulated by changing the fluid composition, is the primary mechanism of mineral reequilibration in the presence of a fluid phase.The applications of these results are a significant improvement in• understanding how one rock type can be transformed to another• using replacement mechanisms to produce more stable coatings on marble cultural heritage• understanding how the reactions between phosphate fertilizer and lime-rich soils can limit the bioavailability of phosphate• applying a better understanding of dissolution mechanisms to contribute to modelling long term stability in nuclear waste repositories• applying "geo-inspired" fabrication of new materials by pseudomorphic replication.The dissemination of the project was through peer-reviewed publications (40 publications in international ISI listed journals with more either already submitted or in preparation), through many international conference abstracts (~90) and presentations and convened special sessions in international conferences.A highlight of the project was the Final International Conference held at the University of Oviedo, Spain from 28 February - 2 March 2012. This was attended by over 100 participants. The Conference Agenda is attached to this report. A further highlight was the Arne Richter Award for Outstanding Young Scientists of the European Geoscience Union (2012) to Dr Encarnación Ruiz- Agudo, a Delta-Min Experienced Researcher Marie Curie Fellow.