Speaker: Postdoctoral Fellow Madeleine Larissa Vickers, University of Oslo, Norway

Abstract
Ikaite is a rare mineral that is chemically identical to calcite, but has a different crystal form which contains water in its structure. It is found naturally growing in places that are characterized by low temperatures and unusual chemistry. First discovered forming tufa towers in the Ikka Fjord in Greenland (from which it gets its name), it has since been discovered growing in seafloor sediments around continents. However, ikaite is only metastable, readily breaking down to a wet crystal mush when removed from its growth environment to ambient temperatures. Throughout the geological record, pseudomorphs after ikaite (called “glendonites”) are found, including in sediments deposited during Greenhouse times. Initially believed to indicate cold paleoclimates, the successful synthesis of ikaite in the lab at warm (>10 °C) temperatures, has led to a debate about the significance of glendonites as possible low-temperature indicators. In this talk I present the evidence for and against glendonites as low-temperature proxy, and demonstrate the unpredictable behaviour of ikaite (both natural and synthetic) under controlled laboratory conditions.

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Relevant paper: https://www.sciencedirect.com/science/article/pii/S0016703722003799?via%3Dihub

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