Antarcticite is an uncommon

calcium chloride Calcium chloride is an inorganic compound, a Salt (chemistry), 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 cal ...

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

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

crystals. It is

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

and has a low

relative density Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

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 (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

where it occurs as crystalline

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

from a highly saline

brine Brine (or briny water) is a high-concentration solution of salt (typically sodium chloride or calcium chloride) in water. In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawat ...

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. ...

, in the west end of

Wright Valley The Wright Valley () is a large east–west trending valley, formerly occupied by a glacier but now ice free except for Wright Upper Glacier at its head and Wright Lower Glacier at its mouth, in Victoria Land, Antarctica. It was named by the VU ...

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 78th parallel south, 78°00'S, and westward from the Ross Sea to the edge of the Ant ...

. 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, 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). Blue holes typically contain tidally influenced water of fresh, ma ...

s on North Andros Island in the

Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...

. 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 Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic c ...

bodies in the

Bushveld complex The Bushveld Igneous Complex (BIC) is the largest Layered intrusion, layered igneous intrusion within the Earth's Crust (geology), crust. It has been tilted and Erosion, eroded forming the outcrops around what appears to be the edge of a great Ba ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. 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, pi ...

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, 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, drywall and blackboard or sidewalk ...

and

celestine Celestine is a given name and a surname. People Given name * Pope Celestine I (died 432) * Pope Celestine II (died 1144) * Pope Celestine III (c. 1106–1198) * Pope Celestine IV (died 1241) * Pope Celestine V (1215–1296) * Antipope Cel ...

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 (geometry), cube becomes a rectangular Pri ...

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.

References

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

See also

References