1. ABOUT THE DATASET --- Title: Dataset for "Polyamines Promote Aragonite Nucleation and Generate Biomimetic Structures" Creator(s): Ouassef Nahi [1], Alexander N. Kulak [1], Shuheng Zhang [1], Xuefeng He [1], Zabeada Aslam [2], Martha A. Ilett [2], Ian J. Ford [3], Robert Darkins [3] and Fiona C. Meldrum [1] Organisation(s): [1] School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK [2] School of Chemical and Process Engineering, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK [3] London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK Rights-holder(s): Copyright 2025 University of Leeds Publication Year: 2025 Description: This dataset supports a study in which we demonstrate that cationic polyamines ranging from small molecules to large polyelectrolytes can exert exceptional control over calcium carbonate polymorph, promoting aragonite nucleation at extremely low concentrations, but suppressing its growth at high concentrations, such that calcite or vaterite form. The data comprises electron microscopy and optical microscopy images of calcite and aragonite crystals, and shows the preparation of aragonite crystals for TEM using FIB. TGA data of crystals including additives is given. The full supplementary information to support the main article is also provided. Cite as: Nahi O., Kulak A.N., Zhang S., He X., Aslam Z., Ilett M.A., Ford I.J., Darkins R. and Meldrum F.C. Dataset for “Polyamines Promote Aragonite Nucleation and Generate Biomimetic Structures” [Dataset] https://doi.org/10.5518/1177 Related publication: Nahi O., Kulak A.N., Zhang S., He X., Aslam Z., Ilett M.A., Ford I.J., Darkins R. and Meldrum F.C. “Polyamines Promote Aragonite Nucleation and Generate Biomimetic Structures”, Adv. Sci. (2023), 2203759. 2. TERMS OF USE --- Copyright [2025] [University of Leeds]. This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/ 3. PROJECT AND FUNDING INFORMATION --- Title: DYNAMIN Dates: Sept 2018 to Aug 2025 Funding organisation: ERC Grant no.: Grant Agreement No. 788968 Title: Crystallisation in the Real World: Delivering Control through Theory and Experiment Dates: Mar 2018 - Feb 2024 Funding organisation: EPSRC Grant no.: EP/R018820/1 Title: Flow-Xl: A New UK Facility for Analysis of Crystallisation in Flow Systems Dates: Mar 2020 - Mr 2023 Funding organisation: EPSRC Grant no.: EP/T006331/1 4. CONTENTS --- Low magnification images: optical micrographs and SEM images of calcite and aragonite crystals images TEM data: TIF files of TEM images of thin sections of aragonite crystals TGA Data: TGA data and analysis of aragonite crystals that have and have not been previously bleached to removed adsorbed PEI FIB-SEM: TIF files of images showing the FIB-SEM preparation of an aragonite crystals for TEM analysis Early stages aragonite: TIF images of early stages of growth of aragonite, and the surfaces of these crystals Supplementary Information: File of SI published to accompany article 5. METHODS --- A full description of the methods and how data were recorded is provided in the associated full publication.