Ikaite Home Page


The ikaite home page has been written in response to the growing interest in the unusual mineral ikaite. This interest has developed following the recent rediscovery of the remarkable underwater spectacle of the ikaite columns of 'The Ikka Column Garden', SW Greenland (Buchardt, et al., 1997; Seaman, 1988). This site provides a brief introduction to the mineral ikaite and contains links that lead you on to learn about some of the known occurrences of natural ikaite or to find out about 'The Ikka Project', a group of scientists studying the deposits in Ikka Fjord.

The mineral ikaite (CaCO3· 6H2O)

Ikaite is the natural form of the compound calcium carbonate hexahydrate (CaCO3.6H2O) which was first synthesized in 1831 by the French chemist Pelouze. Pelouze identified it as a phase of calcium carbonate which was subsequently found to be stable at room temperatures only under high pressures (>5Kb) (Marland, 1975). Calcium carbonate hexahydrate can be grown in the laboratory and exist in a metastable state at Earth surface pressures, under very specific conditions (Pelouze, 1831, Brooks et al. 1950). Such conditions were identified as a source of calcium and carbonate ions, a cold water environment and the presence of a calcite nucleation inhibitor which acts to prevent the preferred reaction which is the precipitation of calcite (Brooks et al., 1950; Marland, 1975). Although the laboratory studies indicate that the conditions for calcium carbonate hexahydrate precipitation are quite specific they are not that uncommon in natural environments.

A little over 100 years since the compound was first synthesised, natural calcium carbonate hexahydrate was identified from a Greenlandic fjord by the Danish mineralogist Hans Pauly. Pauly made the discovery that beautiful mineral columns growing in Ikka Fjord (formerly written Ika Fjord) near Ivittuut, in SW Greenland (Pauly, 1963) were formed from a hitherto unknown mineral. Pauly identified the mineral as calcium carbonate hexahydrate and called it 'ikaite' after the fjord in which it grew. This location is now the type locality for ikaite and is being intensively studied by The Ikka Project.

A number of subsequent discoveries of natural ikaite have since been made the first of these being that of Suess et al. who discovered large amber coloured crystals of ikaite embedded in a deep water core recovered from the Bransfield Straight of the Antarctic shelf from a water depth of 1950 metres (1982). These later discoveries suggest that natural ikaite has two modes of occurrence: firstly as individual, often large crystals, growing displacivly in organic rich mud and secondly as free growing ikaite into a solution.

The metastable nature of ikaite creates problems when attempting to collect it or study it in the laboratory because at room temperature it will quickly disintegrate into a mush of hydration water and calcite crystals. Ikaite may well be a common mineral that is frequently overlooked or missed unless special care is taken to preserve cores or specimens in which it might occur.


Brooks, R., Clark, L. M., & Thurston, E. F., 1950. Calcium Carbonate and its hydrates. Philisophical Transaction of the Royal Society of London. 243. serial A861, 145-167.

Buchardt, B., Düwel, L., Kristiansen, A., Pedersen, G. H., Stockmann, G., Thorbjørn, L., Westergaard. D., 1996. En naturskabt søjlehave I Ikkafjorden I Sydvestgrønland. Naturens Verden, 250. 241-250.

Buchardt, B, Seaman, P. G., Düwel, L., Kristiansen, R. M., Kristiansen, A., Pedersen, G. H., Stockmann, G., Thorbjørn, L., Vous, M., Whiticar, M. J., & Wilken, U., 1997. Submarine columns of ikaite tufa. Nature. November 13. 390 issue number 6656.

Marland, G., 1975. Stability of calcium carbonate hexahydrate (ikaite). Geochimica et Cosmochimica Acta, 39, 83-91.

Pauly, H., 1963b. Ikaite - nyt mineral der danner skaer. Naturens Verden, June 1963. 168 - 171 & 186-192.

Pelouse, J., 1831. Sur la production artificielle du carbonate de chaux cristallise, et sur deux combinaisons de ce sel avec l'eau: Ann. Chim. Phys, ser. 2, 48, 301-307.

Seaman, P. G., 1998. Ikaite formation in a fjord environment with special reference to Ikka fjord. Unpublished Ph. D. thesis. University of London. 258 pages.

Suess, E., Balzer, W., Hesse, K-F., Muller,P.J., Ungerer, C.A., & Wefer,G., 1982. Calcium Carbonate Hexahydrate from Organic-Rich Sediments of the Arctic Shelf: Precursors of Glendonites. Science, 1216, 1128-1130.

Further reading

Dickens, B. & Brown, W. E., 1970. The crystal structure of calcium carbonate hexahydrate at 120°. Inorganic Chemistry, 9. 480-486

Shearman, D. J. & Smith, A. J., 1985. Ikaite, the parent mineral of jarrowite-type pseudomorphs. Proceedings of the Geologists' Association of London, 96, 305-314.

Related links

The Imperial College Greenland Diving Expedition, 1995.

Mineralogical Database entry

This Web site has been written by:

P. Seaman (PaulS@geo.geol.ku.dk) and B. Buchardt, Geological Institute, University of Copenhagen, Denmark. June 1998.

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