Eur. J. Mineral., 33, 249–282, https://doi.org/10.5194/ejm-33-249-2021,https://doi.org/10.5194/ejm-33-249-2021, 2021
Olivine, a ferromagnesian orthosilicate, is the most abundant mineral in Earth’s upper mantle but also in Mars' and Venus'. The olivine atomic structure is also used to manufacture lithium batteries. Like any other crystalline solid, olivine never occurs with a perfect crystalline structure: defects in various dimensions are ubiquitous. In this contribution, I review the current state of the art of defects in olivine and several implications for key processes in geodynamics.