Thénardite

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Thénardite
Thenardite-215859.jpg
Stage made from two thénardite crystals from Soda Lake in Carrizo Plain , San Luis Obispo County , California, USA (size: 5.2 by 3.3 cm)
General and classification
chemical formula α-Na 2 [SO 4 ]
Mineral class
(and possibly department) 		Sulfates (and relatives)
System no. to Strunz
and to Dana 		07.AC.25 ( 8th edition : VI / A.07)
02/28/03/01
Similar minerals Mirabilite
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Fddd (No. 70)Template: room group / 70
Lattice parameters a  = 9.83  Å ; b  = 12.30 Å; c  = 5.87 Å
Formula units Z  = 8
Twinning Penetration twins according to {001} and {100}
Physical Properties
Mohs hardness 2.5 to 3
Density (g / cm 3 ) measured: 2.664; calculated: 2.66
Cleavage completely after {010}
colour colorless, white, white-gray, white-yellow to light brown, reddish-white
Line color White
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.471
n β  = 1.477
n γ  = 1.484
Birefringence δ = 0.013
Optical character biaxial positive
Axis angle 2V = measured: 83 °; calculated: 86 °
Other properties
Chemical behavior water soluble, bitter taste
Special features Fluorescence: bright white (long wave), yellow-green (short wave)

Thénardite (formerly thenardite ) is a rather rarely occurring mineral from the mineral class of " sulfates ( and relatives )". It crystallizes in the orthorhombic crystal system with the composition α-Na 2 [SO 4 ], so from a chemical point of view it is an anhydrous sodium sulfate .

Thénardit usually develops granular aggregates and crusts of white color with a bluish tinge. Colorless thenardite is also known. As with mirabilite, larger crystals are rare.

Etymology and history

The mineral was first discovered at the salt lake of Espartinas near Aranjuez in the Spanish municipality of Madrid and described in 1826 by José Luis Casaseca , who named it after the French chemist Louis Jacques Thénard (1777–1826).

In older publications, the mineral name is spelled thenardite (without acute above the e), which does not, however, comply with the specifications for mineral naming of the IMA, according to which, for example, minerals that are named after a person must be spelled of the name is adopted (the only exceptions are spaces and capital letters, which are removed from the mineral name). The inconsistent spelling of their names for many minerals was initially corrected with the publication “Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks” in 2008 and for the Thénardit 2014 in the 20th newsletter of the IMA / CNMNC made up for. Since then, Thénardit has been used internationally in the spelling with the associated acute.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , Thénardite belonged to the mineral class of "sulfates, selenates, tellurates, chromates, molybdates and wolframates" and there to the department of "anhydrous sulfates without foreign anions ", where he was with Arcanit and Mascagnin formed a separate group.

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 the Thénardite to the class of "sulfates (selenates, tellurates, chromates, molybdates and wolframates)" and there in the department of “Sulphates (selenates etc.) without additional anions, without H 2 O”. However, this section is further subdivided according to the size of the cations involved , so that the mineral can be found in the sub-section “With medium-sized and large cations” according to its composition, as the only member forming the unnamed group 7.AC.25

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Thénardite to the class of "sulfates, chromates and molybdates" and there in the department of "sulfates". Here he is to be found as the only member of the unnamed group 02/28/03 within the subdivision of " Anhydrous acids and sulfates (A + ) 2 XO 4 ".

Crystal structure

Thénardite crystallizes orthorhombically in the space group Fddd (space group no. 70) with the lattice parameters a  = 9.83  Å ; b  = 12.30 Å and c  = 5.87 Å and 8 formula units per unit cell . Template: room group / 70

properties

Chemical properties

Thénardit is easily soluble in water and has a bitter taste. In humid conditions it absorbs water, breaking down into mirabilite.

Physical Properties

It shows white fluorescence under short-wave UV light and yellow-green fluorescence under long-wave UV light .

Education and Locations

Thenardite to mirabilite pseudomorphism from Boron in Kern County , California, USA

Thénardite is typically formed in evaporites under arid conditions. It also occurs as a secondary mineral in the form of efflorescence on various rocks or minerals. Thenardite is typically associated with blödite , epsomite , glauberite , gypsum , mirabilite , soda and rock salt . A chemically similar sodium sulfate that occurs in nature is mirabilite. This is the corresponding decahydrate of thenardite. Since these minerals only differ in the amount of crystal water, the corresponding pseudomorphoses between them are possible.

As a rather rare mineral formation, Thénardite can sometimes be abundant at various sites, but overall it is not very common. Around 200 sites are known to date (as of 2011).

Well-known locations are:

Carrière Francon, Montréal, Québec
Aguas Blancas, Region d'Antofagasta
Avion, Pas-de-Calais, Nord-Pas-de-Calais

Furthermore, Thénardite can form as efflorescence, like the other sulfates ( pentahydrite , hexahydrite , epsomite ), on volcanic fumaroles . Well-known sites are Mount Vesuvius and Mount Etna in Italy . Thénardite deposited via fumarole activity was first described by Scacchi in 1855. He called the mineral pyrotechnite .

use

Thénardite is a "standard mineral" used to describe the chemical composition of rocks according to the CIPW standard .

In the medicine

Like other water-soluble sulfates (e.g. Mirabilit), Thénardit can be used as a laxative .

See also

literature

  • JL Casaseca: Thenardite . In: The Annals of Philosophy . tape 12 , 1826, pp. 312–314 (English, available online at rruff.info [PDF; 280 kB ; accessed on March 3, 2019]).

Web links

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

Individual evidence

  1. ↑ a b c d e f 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.  366 .
  2. ↑ Webmineral - Thenardite (English)
  3. ↑ Thénardite . 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; 67  kB ; accessed on March 3, 2019]).
  4. ↑ a b c d e f Thénardite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 3, 2019 .
  5. ^ JL Casaseca: Analyze d'une nouvelle Substance minérale (la thenardite) . In: Annales de chimie et de physique . tape 32 . Crochard, 1826, p. 308 ( limited preview in Google Book Search [accessed March 3, 2019]).
  6. ↑ 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.  666 .
  7. ↑ Ernest H. Nickel , Joel D. Grice: The IMA Commission on New Minerals and Minerala Names: Procedures and Guidelines on Mineral Nomenclature . In: The Canadian Mineralogist . tape  36 , 1998, pp. 10–11 (English, available online at cnmnc.main.jp [PDF; 336 kB ; accessed on March 3, 2019] section Choice of a new mineral name ).
  8. ^ Ernst AJ Burke: Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks . In: Mineralogical Record . tape 39 , no. 2 , 2008 (English, available online at cnmnc.main.jp [PDF; 2.8 MB ; accessed on March 3, 2019]).
  9. ↑ PA Williams, F. Hatert, M. Pasero, SJ Mills: IMA Commission on new minerals, nomenclature and classification (CNMNC) Newsletter 20 New minerals and nomenclature modifications approved in 2014 . In: Mineralogical Magazine . tape 78 , 2014, p. 549–558 (English, available online at rruff.info [PDF; 106 kB ; accessed on March 3, 2019]).
  10. ↑ Malcolm Back, William D. Birch, Hans-Peter Boja and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2014. (PDF 1551 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2014, accessed March 3, 2019 .
  11. Jump up ↑ Peter Tarassoff, László Horváth, Elsa Pfenninger-Horváth: Famous mineral localities: The Francon Quarry, Montreal, Quebec, Canada . In: Mineralogical Record . tape 37 , no. 1 , 2006, p. 5–60 (English, table of contents available online at mineralogicalrecord.com [accessed March 3, 2019]).
  12. ^ Charles Palache , Harry Berman , Clifford Frondel : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana . tape  2 . Yale University, New Haven 1951, pp. 406 (English).
  13. ↑ M. Naze-Nancy Masalehdani, Florias Mees, Michel Dubois, Yvan Coquinot, Jean-Luc Potdevin, Michel Fialin, Marie-Madeleine Blanc-Valleron: Condensate minerals from a burning coal-waste heap in Avion, Northern France . In: The Canadian Mineralogist . tape 47 , no. 3 , 2009, p. 573–591 , doi : 10.3749 / canmin.47.3.573 (English, available online at sciences-de-la-terre.univ-lille1.fr [PDF; 1.6 MB ; accessed on March 3, 2019]).
  14. ↑ Adolf Kenngott: Overview of the results of mineralogical research in the years 1856 and 1857 . Published by Wilhelm Engelmann, Leipzig 1859, p. 28 ( available online at archive.org  - Internet Archive ).