Antarcticit
| Antarcticit | |
|---|---|
| General and classification | |
| other names |
IMA 1965-015 |
| chemical formula | CaCl 2 • 6 H 2 O |
|
Mineral class (and possibly department) |
Halides |
|
System no. to Strunz and to Dana |
3.BB.30 ( 8th edition : III / A.12) 02/09/06/01 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | 32 |
| Space group | P 321 |
| Lattice parameters | a = 7.89 Å ; c = 3.95 Å |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 2 to 3 |
| Density (g / cm 3 ) | 1.715 |
| Cleavage | along {0001} perfectly |
| colour | colorless |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.55 n ε = 1.495 |
| Other properties | |
| Chemical behavior | well soluble in water |
Antarcticit (also Antarctic ) is a very rare mineral from the mineral class of halides . It crystallizes in the trigonal crystal system with the chemical composition CaCl 2 • 6 H 2 O, so it is chemically a water-containing calcium chloride . The mineral forms aggregates of colorless, needle-like, up to 15 cm large crystals .
Special properties
The mineral is very hygroscopic and easily dissolves in water.
Etymology and history
The mineral was first found on December 30, 1963 by Tetsuri Torii in the type locality , the Don Juan Lake , a 100 x 300 meter, but only 10 cm deep, highly saline lake in the Wright Valley in Victoria Land ( Antarctica ). It was named after the continent Antarctica, on which the type locality is located.
classification
In the Strunz system , Antarcticit is counted among the simple halides. After the 8th edition , it forms together with bischofite , Eriochalcit , hydrohalite , Nickelbischofit , Rokühnit and Sinjarit a group. In the 9th edition it forms a separate subgroup of the simple, water-containing halides with a metal to halide ratio of 1: 2.
In the Dana systematics , it forms a separate subgroup of halides without and containing water of crystallization with a ratio of metal to halide of 1: 2.
Education and Locations
Antarcticit only crystallizes from highly salty solutions under very dry conditions. Depending on the composition of the mineral, a high calcium and chloride content is particularly important. The water of Don Juan Lake is so salty that it does not freeze even in the Antarctic winter. Furthermore, the mineral can arise in the transition from salt water to fresh water in blue holes and as inclusion in quartz in mafic pegmatites . Crystallized antarcticite made of highly saline water, it is with halite , gypsum and Celestine socialized .
Only a few sites are known of the very rare mineral. In addition to the type locality, Antarcticit was only found in the Mary Kathleen mine in Mount Isa ( Australia ), the island of North Andros belonging to the Bahamas, Preissac in the Canadian province of Québec , Schelesnogorsk-Ilimski in Russia , the Driekop mine in the Bushveld- Complex ( South Africa ) and Bristol Lake , a salt flat in the US state of California .
Crystal structure
Antarcticit crystallizes in the trigonal crystal system in the space group P321 with the lattice parameters a = 7.89 Å and c = 3.95 Å and one formula unit per unit cell .
See also
Individual evidence
- ↑ a b Antarcticit at mindat.org (engl.)
- ↑ a b T. Torii, J. Ossaka: Antarcticite: A New Mineral, Calcium Chloride Hexahydrate, Discovered in Antarctica. In: Science. 149, 1965, pp. 975-977, doi : 10.1126 / science.149.3687.975 .
- ^ New Dana Classification of Halide Minerals
- ^ Antarcticit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101.
- ↑ Antarcticit at mindat.org (Engl.)
literature
- Antarcticit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).
- Tetsuya Torii, Joyo Ossaka: Antarcticite: A New Mineral, Calcium Chloride Hexahydrate, Discovered in Antarctica . In: Science . 1965, 149, pp. 975-977, doi : 10.1126 / science.149.3687.975 .