AbstractElectron backscatter diffraction (EBSD) originated in materials science and has transferred to biomineral research providing insight into fossil and modern biominerals. An electron microscopy technique,EBSDrequires a fine polished sample surface where the electron beam diffracts in the first few lattice layers, identifying mineral, polymorph and crystallographic orientation. The technique is particularly well suited for the analysis of modern and fossil calcium carbonate biominerals, where it provides key insight into biological control of mineral formation such as in molluscs and brachiopods.EBSDreadily identifies original and secondary mineralogy, which helps to inform our understanding of biomineral evolution such as the identification of original aragonite inSilurian trimerellid brachiopods. As a technique to identify and thus avoid the inclusion of secondary minerals in proxy organisms such as corals,EBSDcan be used to ensure accuracy of palaeoproxy data. Even when fossil systems have no modern equivalents,EBSDcan provide key data to determine functional mechanisms such as in the lenses of schizochroal eyes of phacopine trilobites. These few examples illustrate thatEBSDis proving to be a valuable component of the palaeontology toolkit.