Glauberite
| Glauberite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | CaNa 2 [SO 4 ] 2 |
|
Mineral class (and possibly department) |
Sulfates |
|
System no. to Strunz and to Dana |
7.AD.25 ( 8th edition : VI / A.08) 04/28/02/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | C 2 / c (No. 15) |
| Lattice parameters |
a = 10.13 Å ; b = 8.31 Å; c = 8.53 Å β = 112.2 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2.5 to 3 |
| Density (g / cm 3 ) | measured: 2.75 to 2.85; calculated: 2.78 |
| Cleavage | perfect after {001}, imperfect after {110} |
| Break ; Tenacity | clamshell; brittle |
| colour | gray, pale yellow, colorless |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass to wax gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.507 to 1.515 n β = 1.527 to 1.535 n γ = 1.529 to 1.536 |
| Birefringence | δ = 0.022 |
| Optical character | biaxial negative |
| Axis angle | 2V = 24 ° to 34 ° (calculated) |
Glauberite is a widespread, but only locally more common mineral from the mineral class of " sulfates and relatives" (see classification ) with the chemical composition CaNa 2 [SO 4 ] 2 and is therefore chemically a calcium - sodium sulfate.
Glauberite crystallizes in the monoclinic crystal system and develops tabular, prismatic or dipyramidal crystals up to ten centimeters in size . In its pure form, glauberite is colorless and transparent. However , it can also take on a gray or slightly yellowish color through foreign admixtures.
Etymology and history
Glauberite was first found in 1808 by M. Dumeril in the type locality near Villarrubia de Santiago in the Spanish province of Castile-La Mancha and described by Alexandre Brongniart . He named the mineral after Johann Rudolph Glauber , who discovered and described sodium sulfate ( Glauber's salt ), which is similar to Glauberite .
Type material of the mineral is in the Muséum national d'histoire naturelle in Paris under the catalog no. 23,400 to 23,402.
classification
In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , glauberite belongs to the division of “anhydrous sulfates without foreign anions ”. The new Strunz'sche mineral classification, however, subdivided here more precisely according to the size of the cations involved and the mineral is therefore now correspondingly in the subdivision “Including large cations”, where it is the only member of the unnamed group 7.AD.25 .
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns glauberite to the sulphate class, but in the section of " anhydrous acids and sulphates with different formulas ", where it is also the only member of the unnamed group 28.4.2 .
Crystal structure
Glauberite crystallizes in the monoclinic crystal system in the space group C 2 / c (space group no. 15) with the lattice parameters a = 10.13 Å ; b = 8.31 Å; c = 8.53 Å and β = 112.2 ° as well as four formula units per unit cell .
properties
Since sodium sulfate is water-soluble, glauberite is also partially water-soluble, and other minerals such as gypsum are deposited . This also happens in humid air, which is why the mineral is not resistant to it and efflorescence and crusts form on gypsum.
Education and Locations
Glauberite forms under dry conditions in evaporites , sediments and salt lakes . Glauberite can also form as precipitation through sublimation in fumaroles , in caves of basaltic lava and in nitrate deposits . In evaporites it is associated with halite , polyhalite , anhydrite , gypsum , thénardite and mirabilite ; in fumaroles with thénardite and sassolin ; in nitrate deposits with Thénardit and Blödit .
As a rather rare mineral formation, glauberite can sometimes be abundant at various sites, but overall it is not very common. As of May 2016, around 130 sites are known to be known. In addition to the type locality, Douglashall near Westeregeln in Saxony-Anhalt ( Germany ), Hallstatt in Austria , Varangéville in France , Antofagasta in Chile , the Great Salt Lake and other places in the United States , Gypsumville in Canada , Lochiel in South Australia , Vulcano in Italy and Surtsey in Iceland .
use
Glauberite is used locally as the basis for the production of sodium sulfate . In the past, it was also mined for soda production.
See also
literature
- Entry to Glauberite. In: Römpp Online . Georg Thieme Verlag, accessed on January 2, 2015.
Web links
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 368 .
- ↑ a b c d Glauberite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.6 kB )
- ↑ a b c d e Mindat - Glauberite
- ^ Alexandre Brongniart: Sur une nouvelle espèce de minéral de la classe des sels, nommée Glauberite. In: Journal des mines. 1808, 133, pp. 5–20 ( pdf )
- ↑ a b Eckard Amelingmeier: Glauberit. In: Römpp Chemistry Lexicon . Thieme Verlag, as of November 2005
- ↑ Mindat - Number of localities for Glauberite
- ↑ Find location list for glauberite in the Mineralienatlas and Mindat