This is a 'preproof' accepted article for Mineralogical Magazine. This version may be subject to change during the production process. DOI: 10.1180/mgm.2022.99 Phenakite and bertrandite: products of post-magmatic alteration of beryl in granitic pegmatites (Tatric Superunit, Western Carpathians, Slovakia) Pavel Uher 1* , Daniel Ozdín 1 , Peter Bačík 1,2 , Martin Števko 2 , Martin Ondrejka 1 , Olena Rybnikova 1 , Štěpán Chládek 3 , Jana Fridrichová 1 , Jaroslav Pršek 4 and Ľubica Puškelová 2 1 Department of Mineralogy, Petrology and Economic Geology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15 Bratislava, Slovakia; 2 Earth Science Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovakia 3 Department of Geological Engineering, Faculty of Mining and Geology, VŠB – Technical University of Ostrava, 17. listopadu 15, 708 33 Ostrava-Poruba, Czech Republic 4 AGH University of Science and Technology, Department of Mineralogy, Petrography and Geochemistry, 30-059 Kraków, Mickiewicza 30, Poland *Author for correspondence, Email: pavel.uher@uniba.sk Running head: Beryl alteration to phenakite and bertrandite Abstract https://doi.org/10.1180/mgm.2022.99 Published online by Cambridge University Press