Langbeinit

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Langbeinit
Langbeinite-553833.jpg
Coarse aggregate of salmon-colored Langbeinite from Carlsbad , New Mexico, USA (size: 4 "× 2.5" × 2.5 "; corresponds to 10.16 cm × 6.35 cm × 6.35 cm)
General and classification
chemical formula K 2 Mg 2 [SO 4 ] 3
Mineral class
(and possibly department) 		Sulphates (selenates, tellurates, chromates, molybdates and tungstates)
System no. to Strunz
and to Dana 		7.AC.10 ( 8th edition : VI / A.03)
04/28/04/01
Crystallographic Data
Crystal system cubic
Crystal class ; symbol tetrahedral-pentagon-dodecahedral; 23
Space group P 2 1 3 (No. 198)Template: room group / 198
Lattice parameters a  = 9.92  Å
Formula units Z  = 4
Frequent crystal faces {100}, {111}, {1 1 1} and others
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) measured: 2.83; calculated: 2.77
Cleavage is missing
Break ; Tenacity clamshell; brittle
colour colorless, white; occasionally pale yellow, pink to red, green or gray
Line color White
transparency transparent
shine Glass gloss
Crystal optics
Refractive index n  = 1.5329 to 1.5347
Birefringence none, as isotropic
Other properties
Chemical behavior slowly soluble in water
Special features piezoelectric and triboluminescent

Langbeinite is a seldom occurring mineral from the mineral class of " sulfates (including selenates, tellurates, chromates, molybdates and tungstates)" with the idealized composition K 2 Mg 2 [SO 4 ] 3 and is therefore chemically a potassium - magnesium sulfate.

Langbeinite crystallizes in the cubic crystal system , but rarely develops crystals with a cubic or octahedral habit with the naked eye . Mostly it is found in the form of kidney, bulbous or granular to massive mineral aggregates . In its pure form, Langbeinite is colorless and transparent. However, due to multiple light refraction due to lattice construction defects or polycrystalline formation, it can also be translucent white and, due to foreign admixtures, take on a pale yellow, pink to red, green or gray color.

Etymology and history

Langbeinite was first discovered in the Wilhelmshall-Anderbeck potash plant in Saxony-Anhalt . The first description was in 1891 by Sylvester Zuckschwerdt , which the minerals by Commerce Adalbert Langbein (1834-1894) from Leopoldshall named to his contributions to the development of Kalisalzindustrie honor in the region.

classification

In the now outdated 8th edition of the mineral systematics according to Strunz , the Langbeinit belonged to the section “Anhydrous sulfates without foreign anions ”, where it was named after the “Langbeinit series” with the system no. VI / A.02 and the other member Manganolangbeinit .

In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. VI / A.03-10 , which in the "Lapis system" corresponds to the section "Anhydrous sulfates [SO 4 ] 2- , without foreign anions", where it forms a common but unnamed group together with calciolangbeinite , efremovite and manganolangbeinite .

The 9th edition of Strunz's mineral systematics , which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also classifies langbeinite into the category of "sulfates (selenates, etc.) without additional anions, without H 2 O". However, this 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 sub-section "With medium-sized and large cations", where the "Langbeinit group" with the system no. 7.AC.10 and the other members Efremovit and Manganolangbeinit.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Langbeinite to the class of "sulfates, chromates and molybdates (including selenates, tellurates, selenites, tellurites and sulfites)" and there in the "sulfates" category. Here, too, he is the namesake in the "Langbeinit series" with the system no. 04/28/04 to be found in the subsection “ Anhydrous acids and sulphates with various formulas ”.

Crystal structure

Langbeinite crystallizes cubically in the space group P 2 1 3 (space group no. 198) with the lattice parameter a  = 9.92  Å and 4 formula units per unit cell . Template: room group / 198

The crystal structure of Langbeinite consists of a framework of [SO 4 ] 2− tetrahedra and Mg 2+ ions in octahedral coordination with respect to the O 2− ions. The K + ions are embedded in the cavities of this framework .

properties

Langbeinite only dissolves slowly in water. A faint glow turns it milky white.

Langbeinit is piezoelectric , which means that, like quartz , it builds up electrical voltage through interval-like elastic deformations. In addition, it is also triboluminescent , which means that it reacts with “cold light emission” when there is strong mechanical stress or friction.

Education and Locations

Like other potash salts , langbeinite is mostly formed by evaporation and is therefore mainly found in marine salt domes , where it occurs in association with carnallite , halite and sylvine , among other things . Langbeinite can, however, also arise from metamorphosis from sylvine, kieserite or polyhalite .

As a rare mineral formation, Langbeinite could only be detected at a few sites, whereby so far (as of 2019) a little more than 40 sites have been documented. In addition to its type locality, the Wilhelmshall potash works, the mineral was also found in the Solvayhall potash works near Bernburg and the Berlepsch mine near Staßfurt in Saxony-Anhalt . Other well-known sites in Germany include Giesel (Neuhof) and the Werra Valley in Hesse, Hänigsen and Wathlingen in Lower Saxony and Ronneburg , Merkers and Unterbreizbach in Thuringia.

In Austria, Langbeinite was found in the Altaussee salt mine in Styria, in the Halltaler salt works in Tyrol and in the Perneck and Hallstatt salt works in Upper Austria.

Other well-known sites include China, France, Japan, Kazakhstan, Pakistan, Poland, Russia, Tajikistan, the Czech Republic and Ukraine as well as in the United States of America (New Mexico).

See also

literature

  • S. Zuckschwerdt: Langbeinit, a new potassium magnesium sulfate . In: Ferdinand Fischer (Ed.): Journal for Applied Chemistry . 1891, p. 356–356 ( available online at rruff.info [PDF; 529 kB ; accessed on April 21, 2019]).

Web links

Commons : Langbeinite  - collection of images, videos and audio files

Individual evidence

  1. ↑ 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.  365 .
  2. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2019 (English).
  3. ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  571-572 .
  4. ↑ a b c d e Langbeinite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 64  kB ; accessed on April 21, 2019]).
  5. ↑ a b c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  6. ↑ Thomas Witzke : Discovery of Langbeinit. Retrieved April 21, 2019 .
  7. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 19, 2019 .
  8. ↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p.  670 .
  9. ↑ Localities for Langbeinite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 21, 2019 .
  10. ↑ List of localities for Langbeinite in the Mineralienatlas and Mindat