We request 4 days of beam-time on ENGIN-X to measure the development of elastic strains in geologically important minerals as a function of uniaxial load. We wish to perform these experiments upon 4 important rock-forming minerals, each from a distinct geological regime, but which cover a range of crystal chemical complexity and an increasing range of structurally bound hydrous components. Moreover, these minerals also have very poorly or incompletely characterised elastic properties despite their inherent contribution to the seismic anisotropy of the Earths lithosphere and asthenosphere. The minerals proposed for study are hornblende, Ca2[Fe4(Al,Fe)]Si7AlO22(OH)2, muscovite, KAl2(Si3Al)O10(OH)2, lizardite, Mg3Si2O5(OH)4 and gypsum, CaSO4.2H2O.