Advances in Glendonite Understanding and Its Potential for Carbon Capture

This article reviews recent advances made by the authors through evaluation of samples in museum collections, in the context of our recent advances in novel observations, of cleavage in a recrystallising ikaite crystal, that may guide future research in understanding the morphology of ikaite, which traditional crystallography has so far not achieved, as traditional crystallography cannot be applied to the morphology of ikaite. Having reviewed over 1100 samples in museum collections, using a combination of morphology and petrology, we are able to define how samples can be classified as glendonite. The topics covered include: (1) a historical review of ikaite and glendonite; (2) evidence supporting ikaite as the precursor mineral of glendonite; (3) the discovery of mega-sized Danish glendonites; and (4) Holocene glendonite coastal sites. Our reassessment of existing knowledge of ikaite shows that when ikaite forms in marine settings, it forms in specific zones before other carbonate phases, and that in sedimentary environments, pressure and pH are not the primary factors controlling its precipitation. Instead, the availability of magnesium (Mg2⁺) and phosphate (PO43−) ions appear to play a more significant role. Furthermore, the conditions required for ikaite precipitation in laboratory experiments differ from those observed in natural ikaite or glendonite formation. Ikaite’s ability to capture carbon at low temperatures and its rapid recrystallisation into its more stable calcite pseudomorph, glendonite, suggest a potential application in carbon capture strategies.