Saturday, February 27, 2010

Ikaite, a mineral named after the Ika Fjord in southwest Greenland

The mineral ikaite is named after the Ika Fjord, now spelled Ikka Fjord, in southwest Greenland. This fjord is about 12 km long and forms the southern border of Ivigtut Peninsula, which is bordered on the north by Arsuk Fjord [1].
Ikaite is a metastable hexahydrate of calcium carbonate with formula CaCO3·6H2O [2]. It forms in lake and sea water in glaciomarine environments at temperatures near 0°C and converts to calcite at higher temperatures. The metastability of this mineral has been illustrated with the description of the treatment of the first samples, secured by a diver in 1962 near skerries (tiny islands) in the Ikka Fjord [1]:
Samples taken fresh from skerries appear as white porous material that is rather friable but forms coherent masses, which disintegrate within a few hours into a wet powder. These and other observations showed that samples had to be stored and shipped with special care. The excellent samples obtained in August from the bottom of small pillars were shipped to Copenhagen in the refrigator aboard the M. S. Nanok S of the Royal Greenland Trading Company.
Ikaite has also been found in ocean floor sediments off the coast of Antartica (in 1982) and in minor amounts in Mono Lake, Mono County in eastern California [3]. Present understanding of the geochemistry of ikaite explains the existence of today's tufa columns at lakes in the Great Basin area, including Pyramid Lake (Nevada) and Mono Lake, as a result of climate warming that pseudomorphed ikaite into tufa since the end of the ice age, when ancient Lake Lahontan and other lakes began their gradual desiccation.

Keywords: mineralogy, geography, Greenland, Mono Lake, history

References and suggested reading
[1] Hans Pauly: “Ikaite”, a new mineral from Greenland. Artic 1963, 16, pp. 264-264.
[2] The mineral and locality database: Ikaite.
[3] Timothy Tierney: Geology of the Mono Basin. Kutsavi Press, Lee Vining, California, 2000
; pp. 59-60.
[4] J. L. Bischoff, J. A. Fitzpatrick and R. J. Rosenbauer: The Solubility and Stabilization of ikaite (CaCO3·6H2O) from 0°C to 25°C: Environmental and Paleoclimatic Implications for Thinolite Tufa. J. Geol. January 1993, 101 (1), pp. 21-33.
[5] B. Buchardt, C. Israelson, P. Seaman and G. Stockmann: Ikaite Tufa Towers in Ikka Fjord, Southwest Greenland: Their Formation by Mixing of Seawater and Alkaline Spring Water. J. Sediment. Res. January 2001, 71 (1), pp. 176-189.
: 10.1306/042800710176.

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