Ikaite

Ikaite is the mineral name for the hexahydrate of calcium carbonate, . Ikaite tends to form very steep or spiky pyramidal crystals, often radially arranged, of varied sizes from thumbnail size aggregates to gigantic salient spurs. It is only found in a metastable state and decomposes rapidly by losing most of its water content once removed from near-freezing water. This "melting mineral" is more commonly known through its pseudomorphs. These pseudomorphs are known by a variety of names, including glendonite, thinolite, jarrowite, and fundylite.

Ikaite is the mineral name for the hexahydrate of calcium carbonate, . Ikaite tends to form very steep or spiky pyramidal crystals, often radially arranged, of varied sizes from thumbnail size aggregates to gigantic salient spurs. It is only found in a metastable state and decomposes rapidly by losing most of its water content once removed from near-freezing water. This "melting mineral" is more commonly known through its pseudomorphs. These pseudomorphs are known by a variety of names, including glendonite, thinolite, jarrowite, and fundylite. Thinolite, (Gr. Thinos = shore) found in the tufa of Mono Lake, California, US Jarrowite, Jarrow, Northumberland, UK Fundylite, Bay of Fundy, Nova Scotia, Canada Gersternkorner, (Ger. = Barleycorn) Gennoishi, (Jp. = hammerstones) Molekryds, (Dan. = Mole Cross), Mors Island, Jutland, Denmark Pseudogaylussite (from semblance to Gaylussite) White Sea hornlets, White Sea and Kola peninsula. Ikaite or its pseudomorphs have been reported as occurring in marine, freshwater, and estuarine environments. The common ingredient appears to be cold temperatures, although the presence of traces of other chemicals, such as nucleation inhibitors for anhydrous calcium carbonate, may also be required. It has also been reported as forming in winter on Hokkaido at a saline spring. Since cold water can be found at depth in the oceans, even in the tropics, ikaite can form at all latitudes. However, the presence of ikaite pseudomorphs can be used as a paleoclimate proxy or paleothermometry representing water near freezing conditions. Thinolite is an unusual form of calcium carbonate found on the shore (Greek: thinos = shore) of Mono Lake, California. This and other lakes now largely in the desert or semi-desert environments of the southwestern US were part of a larger post-glacial lake that covered much of the region near the end of the last glaciation. It is thought that at this time, conditions similar to that of the Ikka fjord allowed for the growth of massive ikaite.

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