Mirabilite
| Mirabilite | |
|---|---|
 |
|
| General and classification | |
| other names |
Glauber's salt |
| chemical formula | Na 2 [SO 4 ] • 10H 2 O |
|
Mineral class (and possibly department) |
Sulfates (and relatives) |
|
System no. to Strunz and to Dana |
07.CD.10 ( 8th edition : VI / C.21) 02.29.02.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 10.51 Å ; b = 10.37 Å; c = 12.85 Å β = 107.8 ° |
| Formula units | Z = 4 |
| Twinning | rarely cross twins after {001} and {100} |
| Physical Properties | |
| Mohs hardness | 1.5 to 2.5 |
| Density (g / cm 3 ) | measured: 1.464; calculated: 1.467 |
| Cleavage | completely after {100}, clear to indistinct after {010} and {001} |
| Break ; Tenacity | shell-like |
| colour | colorless, white, yellowish white, greenish white |
| Line color | White |
| transparency | transparent to opaque |
| shine | Glass gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.396 n β = 1.410 n γ = 1.419 |
| Birefringence | δ = 0.023 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 75 °; calculated: 74 ° |
| Other properties | |
| Chemical behavior | Easily soluble in water and dehydrating |
| Special features | cold, salty to bitter taste; yellow flame in front of the soldering tube (Na) |
Mirabilit , also known as natural Glauber's salt (in older literature also dignified Glauber's salt ), is a rather seldom occurring mineral from the mineral class of sulfates ( and relatives ). It crystallizes in the monoclinic crystal system with the chemical composition Na 2 [SO 4 ] · 10H 2 O, so it is chemically seen a sodium sulphate - decahydrate .
Mirabilit usually develops short to long prismatic crystals up to about 10 cm in length, but also block-shaped, granular or massive mineral aggregates and crusty coatings. Fresh samples are initially colorless and transparent, the surfaces show a glass gloss . In dry air, however, Mirabilit dehydrates very quickly, that is, it loses its crystal water and dries out, whereby it transforms into Thénardite and turns matt white. Mirabilit can also take on a yellowish-white to greenish-white color through foreign admixtures.
With a Mohs hardness of 1.5 to 2.5, mirabilite is one of the soft minerals that, like the reference mineral gypsum (2), can be scratched with the fingernail.
Special properties
Mirabilit is not only sensitive to dehydration, it is also easily soluble in water and can dissolve itself in its own crystal water. Even in case of excessive humidity dissolve the crystals relatively quickly. Mineral samples should therefore always be kept in completely dry and airtight containers.
Mirabilit initially feels cool on the tongue, but then tastes salty to bitter. A yellow flame color appears in front of the soldering tube , which is an indication of the sodium content .
Etymology and history
The name Mirabilit goes back to the Latin name sal mirabilis , which means something like "amazing salt". Johann Rudolph Glauber (1604–1670) chose this name when he discovered an unknown salt with a laxative effect while analyzing mineral water in 1626. In 1658 he was also able to produce the salt artificially by reacting table salt with sulfuric acid. After the discovery of natural sodium sulfate, Wilhelm Ritter von Haidinger named the new mineral in 1845 after the old name sal mirabilis "Mirabilit".
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the mirabilite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates and tungstates" and there to the department of "water-containing sulfates without foreign anions ", where it belongs together with Syngenit the "Mirabilit-Syngenit Group" with the system no. VI / C.21 and the other members Eugsterit , Hydroglauberit , Koktait , Lecontit , Matteuccit and Wattevillit formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns mirabilite to the class of "sulfates (selenates, tellurates, chromates, molybdates and wolframates)" and there in the department of "Sulphates (selenates etc.) without additional anions, with H 2 O". However, this section is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the subsection “With only large cations”, where it is the only member of the unnamed group 7.CD.10 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns mirabilite to the class of "sulfates, chromates and molybdates" and there in the category of "water-containing acids and sulfates". Here he is to be found as the only member of the unnamed group 02/29/02 within the subdivision of " Water-based acids and sulfates with (A + ) 2 XO 4 • x (H 2 O) ".
Education and Locations
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Mirabilite forms in evaporites under arid conditions. There it crystallizes from supersaturated sodium sulphate solutions , such as those found in saline springs or in salt plains . In addition to Thénardite, accompanying minerals include aphthitalite , blödite , epsomite , gypsum , glauberite , halite and trona .
As a rather rare mineral formation, mirabilite can sometimes be abundant at various sites, but overall it is not very common. So far (as of 2013) around 180 sites are known.
In Germany, the mineral was among others at Heringen and Philippsthal in the Hessian Werra valley ; near Hänigsen , Wathlingen and on the Lüneburg Kalkberg in Lower Saxony; near Friedland in Mecklenburg-Western Pomerania; Found in the "Mathias" gypsum mine near Rammelfangen in Saarland and in the "Willi Agatz" mine near Dresden in Saxony.
In Austria, mirabilite has so far mainly occurred in the Salzburg region , where it has been found in several gypsum and salt pits or in thermal springs . The mineral was also found in the Pfennigbach near Puchberg am Schneeberg in Lower Austria, in the salt mines of Altaussee (Styria) and Hall in Tyrol, as well as in Upper Austria at the Bad Ischler Salzberg , near Hallstatt and in the Hintersteiner Alp near Spital am Pyhrn in Upper Austria.
In Switzerland, mirabilite has so far been found in the gypsum mine near Birmenstorf in the canton of Aargau, in Martigny in the canton of Valais, in the salt mine of Bex in the canton of Vaud. Mirabilite deposits were also found in the Faustloch cave in the Bernese Oberland and in the Réseau des Morteys cave near Charmey in the canton of Friborg.
Well-known sites for mirabilite include the Tăușoare Cave in Romania and the Death Valley National Park in the US state of California. Other sites are in Egypt, Antarctica, Argentina, Australia, Bolivia, Chile, China, England, France, Italy, Japan, Canada, Madagascar, Mexico, the Netherlands, Norway, Poland, Russia, Slovakia, Spain, Tajikistan, the Czech Republic , Turkey, Turkmenistan, Ukraine, Hungary and other states of the USA.
Crystal structure
Mirabilit crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 10.51 Å , b = 10.37 Å, c = 12.85 Å and β = 107.8 ° and four Formula units per unit cell .
use
As a raw material
Mirabilit is a raw material for making soda .
In the medicine
Except for the crystal water, mirabilite is chemically identical to Glauber's salt . Like this it can be used as a laxative . In traditional Chinese medicine , it is used as a laxative under the name máng xiāo (芒硝).
See also
literature
- Luc Funcken, Muriel Moens, Philipp Hauselmann: Synthesis of research in the fisthole since 1987. Swiss Society for Speleology: Stalactite 50, 1. Speleo Projects, Allschwil, Switzerland, 2000.
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, Stuttgart 1978, ISBN 3-432-82986-8 , p. 611 .
- Hans Jürgen Rösler: Textbook of Mineralogy . 5th edition. German publishing house for basic industry, Leipzig 1991, ISBN 3-342-00288-3 , p. 666 .
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 , pp. 306 .
- Swiss Society for Speleology: Stalactite 46, number 1. Speleo Projects, Allschwil, Switzerland, 1996.
Web links
- Mineral Atlas: Mirabilit (Wiki)
- Maricopa.edu: Glendale Community College - Earth Science Image Archive - Mirailite ( Memento from June 29, 2011 in the Internet Archive )
- American mineralogist (1917)
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 392 .
- ↑ Webmineral - Mirabilite (English)
- ↑ a b c d Mirabilite , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.6 kB )
- ↑ a b c d Mindat - Mirabilite (English)
- ^ FA Reuss: About a dignified Glauber's salt in the area of Saidschütz and Saidlitz , in: Crell's Chemischen Annalen , Volume 2 (1791), p. 18 (quoted in Encyklopadie der Gesamt Chemie , Volume 1, parts 1-3, p. 433 ) in Google Book Search
- ↑ James C. Hill: Johann Glauber's discovery of sodium sulfate - Sal Mirabile Glauberi. In: Journal of Chemical Education. 56, 1979, p. 593, doi : 10.1021 / ed056p593
- ↑ Mindat - Number of localities for Mirabilit
- ↑ Luc Funcken, Muriel Moens, Philipp Hauselmann: Synthesis of the research in the fist hole since 1987. Stalactite 50, 1. S. 12. Speleo Projects, Allschwil, Switzerland, 2000.
- ↑ Swiss Society for Speleology: Stalactite 46, 1st p. 49, 1996.