The Legend of Ikka FjordDiscovery of the Mineral by Science
Possible Uses of Ikaite & its Pseudomorphs
Inuit and Viking legend recounts a tale of how invaders were driven out onto the thin ice of a frozen fjord, the ice gave way and they plunged through the icy waters to their death. As they did so, they became rooted on the bottom as petrified statues. The taller columns often terminate in a hand like form, as if they are reaching for air. They say that the different size columns represent the warriors and their families, mothers, children and all. Even today if you peer through the waters of the fjord in the still of the morning, you can see them standing their motionless, preserved for eternity.
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As early as 1819 Daniell described the synthetic hydrates of calcium carbonate (i.e. those with water molecules within their molecular structure). In 1831 Pelouze was the first to synthesise the hexahydrate. However, it was thought that the material could not occur naturally because of its high instability. Ikaite quickly decays to anhydrous calcium carbonate and water at normal room temperatures and specimens of ikaite are extremely rare.
In August 1962 all this changed with the chance discovery by Hans Pauly, a danish geologist working for the local cryolite mining company. He was taken on a picnic by the local danish navy officers to Ikka Fjord, where they discussed the columns with him and then sent down a navy diver to obtain a sample for him to study. This sample was then left to stand whilst they continued with their lunch on land. On returning to their boat several hours later Pauly observed that the mineral had decayed and realised that this was a new mineral. More samples were then collected, but Pauly had to keep them in a cold condition until he could return to his Copenhagen laboratory several months later.
Pauly went on to discover that the mineral was a hydrated form of calcium carbonate and by the change in weight, suggested that it was the hexahydrate. Pauly named his new mineral Ikaite after the fjord. Un-fortunately for science (or fortunately for the ICGDE members!), Pauly published his discovery in danish, in Naturens Verden (1963) - IKAIT, Nyt mineral der danner sk?r - and though a small note on the discovery was also published in the American Mineralogist (1964), the discovery went largely un-noticed by the geological community.
An important study of ikaite was made by Marland in 1975 who synthesised the mineral using the following 'recipe' - 100ml of 0.1M CaCl2 plus 100ml 0.1M K2CO3 added dropwise from burettes over 2-3 hours to 400 ml of H20 containing 1g KOH and held at 2oC - modified from Johnson et al (1916), to study the minerals' stability and conditions for formation. From this study, Marland concluded that whilst ikaite is the stable mineral phase of calcium carbonate at high pressures (>3 kilobars), its existence at earth surface temperatures and pressures could only be in a metastable state. He further noted that even in the deepest ocean basins, pressures are only one third of that required to reach the ikaite stability field.
Very specific conditions are therefore necessary if ikaite is to be precipitated close to or at normal surface pressures. Certain elements are essential to ikaite precipitation, these being sources of calcium and bicarbonate. It appears that for ikaite to grow in the place of the preferred precipitation of calcite, the presence of an inhibitor is also needed and this process will only occur in a very cold water environment.
Quite why ikaite is forming in Ikka Fjord is still unknown although it is understood that the above pre-requisites must be satisfied. All that was directly known prior to the expedition, were Pauly's observations - importantly that the mineral was precipitating from the waters of springs mingling with the cold fjord water (2-3 C) and a detailed geological investigation of the country rocks and map of the carbonatite-syenite intrusion complex made by Emeleus in 1963, which identified a possible source of the bicarbonate in the carbonatite. The carbonatite-syenite intrusion also offered a likely source of an inhibitor, in the form of phosphate.
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In 1977 Kaplan (following discussions with Tatanskii), first postulated that ikaite may have been the precursor of a number of enigmatic pseudomorphs found throughout the geological record and first described by Friesleben in 1827.
This point was taken on by a number of geologists:
Suess et al (1982), who after making the first discovery of ikaite since Pauly, on the Antarctic shelf, suggested that ikaite was the precursor of a group of unusual calcitic pseudomorphs known as the Glendonites, which are found associated with glacial marine deposits of Permian to Recent age.
Shearman and Smith in 1985 who confirmed the parent identity of the jarrowite-type (or thinolite) pseudomorphs as being ikaite.
Shearman et al (1989), also suggested that the thinolites in the Quaternary tufas & great tufa mounds of the Lahontan & Mono lake basins of the western United States, were also formed after ikaite. This hypothesis was enhanced in 1991, following the discovery of the seasonal growth of ikaite along the southern shoreline of Mono Lake.
Pseudomorphs now believed to be 'after ikaite' are found in strata ranging from the Precambrian (Dalradian) to Quaternary across the World. A notable example are the pseudomorphs preserved in precious opal from Cretaceous rocks at White Cliffs New South Wales. Australia.
With the possible exception of Mono Lake in its recent past, nowhere has ikaite been found forming the spectacular stalagmite-like columns found in Ikka Fjord. The remarkable structures now sub-aerially exposed on the south shore of Mono Lake, are wonderfully described by Russell the great American geologist of the last century. Russells' poetic description is reproduced here (Russell, I. C.,1889).
The character of the tubular lithoid tufa mentioned in the preceding descriptions is well shown on the southern shore of the lake, about a mile east of the end of the Mono Craters. Several acres at this locality are covered with irregular trunks, from a few inches to five or six feet in height, with a diameter of six or eight inches. The appearance of a few of these peculiar deposits is shown on Plate 1. The formation as a whole resembles a forest of gnarled and contorted trunks and stumps changed to stone. The trunk-like masses are not simple tubes with solid walls, but are traversed by many irregular passages which open at the top in a number of small orifices. They are porous and cellular throughout. On the sides there are also numerous openings about which tufa has been deposited, thus forming knobs and irregularities. At times, two or more separate trunks are united by lateral branches, but usually each one is the result of a single independent growth. These tubular trunks differ, however, from the core of lithoid tufa in the larger crags, in that they spring from independent bases and are spread over a broad area, instead of being grouped about a common center and united so as to form a single mass, expanding sheaf-like at the top. The impression which this imitation forest leaves on the mind is that it is in some way weird and uncanny. The silent and motionless trunks with their uncouth shapes recall Dante's description of the wood of the suicides. This fancy is heightened by the proximity of a sea whose flowerless shores seem scarcely to belong to the habitable earth.
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Doug Shearman, continued to be interested in the mineral and pursued the subject, following up leads on further discoveries of ikaite and possible pseudomorphs after ikaite. His aim was to get an expedition back to Ikka fjord and for further studies to be carried out. His wish became more realistic in 1991 whilst examining a student, Paul Seaman who was completing his degree and was also a diver. Through further discussion with fellow divers Anthony Taylor and James Passmore the idea became a reality and the expedition went ahead in the summer of 1995.
Though the mineral had since been discovered in other global locations, these locations were either seasonal or in deep sea sediments and therefore not readily accessible, as opposed to Ikka Fjord, where the ikaite was known to occur perennially. Though the Ikka Fjord area has been studied in some detail with regards the Precambrian carbonatite - syenite intrusive complex, the two expeditions of the summer of 1995 (Copenhagen University & ICGDE), were the first time that scientists had re-visited the holotype locality to re-study the mineral.
Due to the nature of Paulys' gravimetric analysis, it wasn't even sure whether the columns of Ikka fjord were indeed calcium carbonate hexahydrate, some other calcium carbonate hydrate, or a mixture of calcium (carbonate and other) hydrates
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Since the Pauly discovery, there have been only six other reported findings of ikaite - in a variety of different geological settings - across the World.
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The occurrence of ikaite in cold water conditions and jarrow-type pseudomorphs in glacial and periglacial sediments point to an obvious use in stratigraphy as a palaeo-geothermometer.
It is also suggested (for several reasons) that an understanding of its formation may be of use to the hydrocarbon industry:
As ikaite forms in near surface conditions at the expense of calcite and other tufaceous deposits, it is thought that an understanding of the role of the inhibitor in this process, (it has been suggested that this may be either organic carbon or phosphates), may be of use to the water softening industry.