Formula: Ca(CO3).6H2O
Hydrated normal carbonate
Specific gravity: 1.77 to 1.8
Streak: White
Colour: Chalky white
Environments
Ikaite is a very rare carbonate that forms in sea water and lake water in anaerobic (oxygen deficient), organic-rich
periglacial (subject to repeated freezing and thawing) and glaciomarine (containing both glacial ice and marine water)
environments near 0oC, readily converting to calcite at higher temperatures
of about 8oC
(HOM, Mindat, Webmin).
Localities
At White Cliffs, New South Wales, Australia, opal
pseudomorphs after ikaite have been found
(KL p259).
At the type locality, Ikka Bund, Ikka Fjord, Sermersooq, Greenland, Denmark, chalklike underwater pillars occur in the inner
part of the fjord, 8 km south of Ivigtut. The pillars reach to within half a metre of the water surface. The temperature at
the base of the pillars was 3oC and 7o at the top. Samples were collected by a frogman and shipped
in a refrigerator at about 4oC
(AM 49.439).
At the Olitsna river, White Sea coast, Karelia Republic, Russia, calcite
pseudomorphs after ikaite have been found (KL p154). These
pseudomorphs are sometimes called "glendonite"
(Mindat).
At Bielo More, Kola Peninsula, Murmansk Oblast, Russia, pseudomorphs of
calcite after ikaite to 10 cm have been found
(Extra Lapis English-4 p23).
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