Fellow mineralogists et al. We are keen to inform you of a Special Session honoring the contributions of Donald D. Hogarth at the upcoming GAC-MAC-IAH-CNC meeting (“Geoscience Beyond Boundaries”) to be held in Ottawa, Ontario, Canada, on May 11-14, 2025. MINERALS_SS_08: Mineralogy - chemical systems related to magmatic, metamorphic and hydrothermal processes. A GAC–MAC meeting hosted by the University of Ottawa provides the perfect setting to celebrate the career of Donald D. Hogarth (1927–2019), eminent mineralogist and historian of science. His name is still closely associated with the classification of pyrochlore-supergroup minerals, including “betafite”, whose status is still being debated. He recognized the presence of carbonatites and fenites in the Gatineau Hills north of Ottawa. He defined new minerals in fenite (fluoro-potassic-magnesio-arfvedsonite) and in the Evans-Lou granitic pegmatite [wakefieldite-(Y) and caysichite]. He delved into the historical aspects of classic mineral-collecting sites in the western Grenville Province. He wrote a book on Martin Frobisher’s Northwest Ventures in the Arctic. He published on lapis lazuli and other gemstones on Baffin Island. Hogarthite, a hydrous silicate of Na, Ca and Ti from Mont Saint-Hilaire, is named in his honour. We particularly invite former students and colleagues to participate in this session. The full technical program is now available online: https://event.fourwaves.com/ottawa2025 Abstracts can be submitted before February 2 ($40 CAD) or February 16 ($60). Please pass along to others who might be interested. HOPE TO SEE YOU IN OTTAWA Robert F. Martin [robert.martin@mcgill.ca] and David R. Lentz [dlentz@unb.ca], co-chairs