However, beyond such case-by-base studies, general structure-property relationships of framework materials are still pretty much an open question. Some studies in the field have started to delineate general trends and highlight the boundaries of the possible properties. For example, Karothu et al. surveyed three decades of published literature on mechanical properties of organic crystals in order to perform an extensive systematic analysis of their values of Young's modulus and hardness. This allowed them to better describe the limits of their mechanical performance as a family of materials, and establish certain broad correlations with, e.g., crystal density. In a seminal work in 2015, de Jong et al. had followed a similar idea on the computational side and mapped the elastic properties of 1,181 inorganic crystalline compounds through DFT calculations. This database of elastic tensors of crystals, integrated as part of the Materials Project database, is a valuable resource for the community and has continued to grow. It accounts for 12,802 inorganic materials to date -we will provide more details on its uses for data-based approaches to materials discovery in section 5.