About the ACA Canadian Division logo

Ikaite - "The Mysterious Mineral of the North"

For its logo, the ACA Canadian Division uses a pseudomorph of Ikaite, as published in an 1884 U.S. Geological Survey Bulletin [Ref. 4] by the famous mineralogist, Edward Salisbury Dana (1849 - 1935) (son of James Dwight Dana (1813 - 1895), an equally famous mineralogist).

Ikaite (pronounced Ikka-ite or to many who like the sound, Ikky-ite,) is a natural mineral of calcium carbonate hexahydrate (CaCO3 · 6H2O) which only forms in waters of near freezing temperatures; making it very eligible for use as a logo by the Canadian Division of the American Crystallographic Association (at least during the fall, winter and spring months). Ikaite forms a variety of eye-catching and dramatic crystal shapes (its "crystal habits"). While described here as the "mysterious mineral of the north", it has been found in many other places around the globe where there are bodies of cold water: e.g., Antarctica, an ocean trench off Japan, and even an equatorial ocean abyssal fan off Africa.

At the earth's surface ikaite is always metastable. It is preserved by the presence of crystallization inhibitors of anhydrous calcium carbonate, such as phosphate. If it is removed from these conditions, it will rapidly decompose into a mush of water and calcium carbonate; hence the nickname of the "melting mineral".

Ikaite (structure refined from neutron powder diffraction data collected on a deuterated sample, Swainson and Hammond [Ref. 7])

Crystallographic Symmetry: Monoclinic
Unitcell: 8.8268 8.3235 11.0532 90.0000 110.5790 90.0000
Crystallographic Spacegroup: C2/c

Ca      0.00000  0.14680 0.25000
C       0.00000 -0.19410 0.25000
O1      0.00000 -0.35010 0.25000
O2      0.02720 -0.11450 0.15760
O3      0.61460  0.72220 0.09130
O4      0.28600  0.05820 0.38280
O5      0.67070  0.88490 0.35890
H1/D1   0.57250  0.68690 0.00170
H2/D2   0.63740  0.80630 0.09050
H3/D3   0.36790  0.10790 0.35310
H4/D4   0.81120  0.59310 0.47250
H5/D5   0.77880  0.88600 0.35390
H6/D6   0.62790  0.99150 0.33070

Ikaite is also of interest in stratigraphy and paleoclimate research due to its unique conditions of formation (freezing water), making it a paleoclimate indicator. It forms as an authigenic mineral, meaning it forms in-situ in these special conditions. Because of its instability, it is never found in old rocks at the earth's surface, and evidence of its past presence is found in the form of "pseudomorphs". Pseudomorph literally means "false shapes", where one mineral possesses the characteristic crystal habit of another due to recrystallization or replacement of the original precursor by another mineral. The replacement pseudomorphs of ikaite include the locality names of Glendonites (Glendon, New South Wales, Australia), Thinolites ((SW USA) [Greek, thinos=shore]), Jarrowites (Jarrow, UK), Fundylite (Bay of Fundy, Canada), Gennoishi (Japanese=hammerstones; Niigata Prefecture, Japan), Gersternkorner (German=barley-corn) and "White Sea Hornets" (Kola Penninsula). Ikaite is usually replaced by an anhydrous form of calcium carbonate as it decomposes. Thus finding these pseudomorphs in sediments indicates that a cold aquatic environment existed in that locale sometime in the past. However, people should be wary of using these pseudomorphs as a paleolatitude indicator of high latitudes, as ikaite can form in cold water anywhere and has been found near the equator.

Discovered in the laboratory by Pelouze in 1865 [Ref. 1], Ikaite was first described in nature by Pauly (1963) [Ref. 2] in the Ikka fjord of southwest Greenland, Danish North America, suspiciously close to Canada. "At this locality it grows in columns of tufa up to 20 m long, apparently forming as a rapid precipitate from a carbonate-rich, fjord-floor natural groundwater seepage." [Ref. 3] This cold ecological environment forms a habitat for a unique species of brine shrimp which are known only to live in columns of Ikaite. The pseudomorphs of ikaite were first described by the famous mineralogist, Edward Salisbury Dana in 1884 [Ref. 4]. Ikaite has also been the subject of extensive dental research by the US Military-Industrial Complex (The American Dental Association in collaboration the US Army Dental Corps) [Ref. 5]. and is also important in the increasingly important field of the cryogenic preservation of shrimp [Ref. 6].

Until recently, it was "assumed" that the pseudomorphs of ikaite were just that, without any real crystallographic proof. Work using the neutron powder diffraction facilities of the National Research Council of Canada, quantitatively linked the morphological crystallographic relationship between ikaite and its pseudomorphs [Ref. 7]. It is the opinion of Swainson and Hammond that ikaite [Ref. 7] is not, as commonly claimed, "a rare mineral"; but that it is probably more common than realized, and it is only the great instability that prevents its detection. It possibly exists in many deep water sediment and ocean cores samples, but the ikaite has already decomposed by the time the samples are ready for study.

References

1. Pelouze, M.J. (1865) Sur une combinaison nouvelle d'eau et de carbonate de chaux. Chemical Review, 60, 429-431.

2. Pauly, H., (1963) "Ikaite", a new mineral from Greenland. Arctic, 16, 263-264.

3. Buchardt, B., Seaman, P., Stockmann, G., Wilken, M.V.U., Duwel, L., Kristiansen, A., Jenner, C., Whiticar, M. J., Kristensen R.M., Petersen, G.H., and Thorbjorn, L. (1997) Submarine columns of ikaite tufa. Nature, 390, 129-130.

4. Dana, E.S. (1884) A crystallographic study of the thinolite of Lake Lahontan: U.S. Geological Survey Bulletin No 12, 429-450. Washington D. C., U.S. Government Printing Office.

5. Dickens, B. and Brown, W. E. (1970) The crystal structure of calcium carbonate hexahydrate at ~-120°C. Inorganic Chemistry, 9, 480-486.

6. A. Mikkelsen, A.B. Andersen, S.B. Engelsen, H.C.B. Hansen, O. Larsen and L. Skibsted, (1999) Presence and Dehydration of Ikaite, Calcium Carbonate Hexahydrate, in Frozen Shrimp Shell Journal of Agricultural and Food Chemistry, 47, 911-917

7. I.P. Swainson and R.P. Hammond (2001) Ikaite, CaCO3·6H2O: Cold comfort for glendonites as paleothermometers, American Mineralogist, 86, 1530-1533,

Some Ikaite web links

(accessible on 18th November 2003)

Ikaite Home Page.

Ikaite Crystal structure data (original dental military data).

Ikaite Crystal structure data (original dental military data).

Ikaite mineral data.

Minerals of Greenland - Ikaite.

Ikaite and related Links.

Ikaite photographs .

Submarine columns of ikaite tufa.

Mineralogy of Ikaite.

Calcite after Ikaite.

Microbial diversity in ikaite tufa columns: an alkaline, cold ecological niche in Greenland.

Ikaite Photo Gallery.

Memorial of Edward Salisbury Dana.