Advances in triaxial compression deformation apparatus design, dynamic X-ray microtomography imaging, data analysis techniques, and digital volume correlation analysis provide unparalleled access to the in situ four-dimensional distribution of developing strain within rocks. To demonstrate the power of these new techniques and acquire detailed information about the micromechanics of damage evolution, deformation and failure of porous rocks, we deformed three centimeter-scale cylindrical specimens of low porosity Fontainebleau sandstone in an X-ray transparent triaxial compression apparatus, and repeatedly recorded three-

A novel method for studying nucleation and growth of CaCO 3 crystals in situ has been developed and tested rigorously. We demonstrate that precise flow control is essential and how this is achieved. The method has the advantage that one may study single crystals of polymorphs that are thermodynamically unstable in collections of many crystals and that one obtains precise and accurate growth rates without any extra assumptions. We also demonstrate that at low supersaturations where 2D nucleation does not occur we measure the growth rate constant of calcite to be 5 times larger than that reported by batch methods and two orders of magnitude larger than measured by AFM. Considering the large interest in calcite growth in for example geoscience, environmental science, and industry we consider that it is important to explain the discrepancy of growth rate constants between different methods. The method presented here can easily be applied to many other minerals.

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