Zircon (ZrSiO4) is renown for being physically robust, and is arguably the most significant accessory mineral because it continues to revolutionize our understanding of the evolution of Earth, Moon and other bodies. But is zircon forever? What happens to this tough little cookie under extreme conditions, where it can be taken to the brink of destruction? In this talk, we will find out exactly how zircon responds to extreme pressure and temperature conditions, under which it can deform plastically, twin, transform to a high pressure polymorph, become granular, ultimately breakdown (dissociate) into various ZrO2 + SiO2 oxides, and even revert to zircon again. All of these transformations occur via specific, predictable crystallographic orientation relationships, enabling us to read zircon’s battle scars to reveal its (often) cryptic history of extreme conditions. We present new pressure-temperature diagrams of the phase transformations of ZrSiO4 and their dissociation products under extreme conditions using available empirical and theoretical constraints. These diagrams provide a context in which to interpret natural samples through shock metamorphism.