Antarcticite is an uncommon

calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide. Ca ...

hexahydrate mineral with formula CaCl₂·6H₂O. It forms colorless acicular

trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...

crystals. It is

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substan ...

and has a low

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...

of 1.715. As its name implies, it was first described in 1965 for an occurrence in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

where it occurs as crystalline

precipitate In an aqueous solution, precipitation is the process of transforming a dissolved substance into an insoluble solid from a super-saturated solution. The solid formed is called the precipitate. In case of an inorganic chemical reaction leading ...

from a highly saline brine in

Don Juan Pond Don Juan Pond is a small and very shallow hypersaline lake in the western end of Wright Valley (South Fork), Victoria Land, Antarctica, west from Lake Vanda. It is wedged between the Asgard Range to the south and the Dais Range to the north. On t ...

, in the west end of

Wright Valley The Wright Valley, named for Sir Charles Wright, is the central one of the three large Dry Valleys in the Transantarctic Mountains, located west of McMurdo Sound at approximately . Wright Valley contains the Onyx River, the longest river in ...

Victoria Land Victoria Land is a region in eastern Antarctica which fronts the western side of the Ross Sea and the Ross Ice Shelf, extending southward from about 70°30'S to 78°00'S, and westward from the Ross Sea to the edge of the Antarctic Plateau. I ...

. This discovery was made by Japanese geochemists Tetsuya Torii and Joyo Ossaka.Antarcticite: A New Mineral, Calcium Chloride Hexahydrate, Discovered in Antarctica, Science 27 August 1965: Vol. 149 no. 3687 pp. 975-977
/ref> It was also reported from brine in

Bristol Dry Lake Bristol Lake is a dry lake in the Mojave Desert of San Bernardino County, California, northeast of Twentynine Palms. Bristol Lake is located southeast of Amboy, California, Amboy and U.S. Route 66 in California, U.S. Route 66, and is also south ...

, California, and stratified brine within

blue hole A blue hole is a large marine cavern or sinkhole, which is open to the surface and has developed in a bank or island composed of a carbonate bedrock ( limestone or coral reef). Their existence was discovered in the late 20th century by fishe ...

s on North Andros Island in the

Bahamas The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to 88% of the ar ...

. It has also been noted within

fluid inclusions image:Inclumed.gif, 250px, Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, crystals of halite, sylvite, gypsum, ...

within

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

in pegmatite bodies in the

Bushveld complex The Bushveld Igneous Complex (BIC) is the largest layered igneous intrusion within the Earth's crust. It has been tilted and eroded forming the outcrops around what appears to be the edge of a great geological basin: the Transvaal Basin. It i ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

. It occurs in association with

halite Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, p ...

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywal ...

and celestine in the California dry lake. A similar mineral, ''sinjarite'', the dihydrate of calcium chloride, crystallizes in the

tetragonal In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a squar ...

system. Sinjarite is semitransparent, with pale pink color. Hydrophilite is a now discredited calcium chloride mineral that is considered to be either antarcticite or sinjarite.Hydrophylite on Mindat
/ref>

References

Halide minerals Trigonal minerals Minerals in space group 150 {{halide-mineral-stub

See also

References