The mechanical properties of snow depend on its microstructure. The fabric of snow was reconstructed in three dimensions using serial sections or X-ray microtomography. A voxel-based finite-element model, with the elements based on the microstructure and ice as the material, was used to calculate the stress distribution in the snow. A small elastic deformation was simulated and the bulk elastic moduli of these samples were determined. The simulated elastic modulus was 3-10 times or 10-100 times larger than previously published measurements. The deviation is possibly caused by the relatively slow deformation rates of the usual tests. This strain-rate effect is well known for pure ice. Locations of stress concentrations can be extracted and compared to the microstructural location of bonds. By this method we are able to determine mechanical properties of thin or extremely brittle snow layers which are otherwise difficult or impossible to measure.