Introduction to the Special Issue in honour of Dr. Edward S. Grew’s 80 ^th Birthday

European Mineralogical Conference in Dublin (2024), held in celebration of Dr. Grew's 80 th birthday.Together, these papers highlight the remarkable breadth of his scientific influence.The seventeen submissions reflect Ed's wide-ranging interests and build on his legacy of discoveries spanning boron, lithium, and beryllium mineralogy; new mineral species and crystallography; rare-element geochemistry; the petrology of igneous and metamorphic rocks; and the changes of minerals through geologic time.Minerals of the garnet supergroup hold a special place for Ed, owing in part to his key role in developing the most recent garnet nomenclature (Grew et al., 2013).Fittingly, this volume includes two contributions that explore different aspects of garnet.The contribution of Galuskin et al. (2025) presents the first terrestrial occurrence of the garnet species rubinite, Ca 3 Ti 3+ 2 Si 3 O 12 previously known only from refractory inclusions in CV3 carbonaceous chondrites.It is considered a marker of extreme reducing conditions.In the pyrometamorphic Hatrurim Complex (Negev Desert, Israel), rubinite has been identified within a phosphide-bearing breccia formed when metasedimentary xenoliths underwent intense pyrometamorphism after being encased in a flamite-gehlenite paralava.In the confluence of garnets and rare earth elements, Harlov (2025) demonstrated that at 900C and 1000 MPa, experiments involving Y 2 O 3 , Sm 2 O 3 , LuPO 4 , EuPO 4 , and 2N NaOH produce rapid metasomatic incorporation of Y and REE into almandine-pyrope garnet by coupled dissolution-reprecipitation.These reactions modify the dodecahedral site through substitutions such as [8] (Y,REE) 3+ + [4] Al 3+ = [8] (Fe,Mg,Mn,Ca) 2+ + [8] Si 4+ .In contrast to sluggish solid-state diffusion, this fluid-mediated process enables efficient Y + REE exchange in garnet during metamorphism, with important implications for Lu-Hf and Sm-Nd geochronology, Yxenotime geothermometry, and the use of Y- 18 O systematics as a tracer of fluid-rock interaction.On a related note, priscillagrewite-(Y) is a Y-,Zr-bearing garnet (Ca 2 Y)Zr 2 Al 3 O 12 .Tourmaline, a boron-bearing mineral supergroup, has been a long-standing focus of Ed's research (e.g.