Ikaite
（重定向自Glendonite）
![](/Images/godic/202501/15/Concretion_and_crystals1224.jpg")
![Ion pair (Ca2+CO32−)0 and hydration cage. Part of the crystal structure of ikaite. Ca (blue) is in dodecahedral coordination with O atoms (red) of the carbonate (black planar) and water molecules, while hydrogen bonds (dotted) between H-atoms (yellow) of the water molecules to the O-atoms of the carbonate ion exist.[13][15]](/Images/godic/202501/15/Ikaite-wiki1224.png")
![Images of thinolite pseudomorphs taken from ES Dana (1884).[21]](/Images/godic/202501/15/Glendonite1224.png")
Ikaite is the mineral name for the hexahydrate of calcium carbonate, CaCO3·6H2O. 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.