Arcanite

from Wikipedia, the free encyclopedia
Arcanite
Arcanite.jpg
Arcanite from the collection of Brigham Young University , Utah
General and classification
other names
chemical formula
  • K 2 [SO 4 ]
  • α-K 2 [SO 4 ]
Mineral class
(and possibly department)
Sulphates (selenates, tellurates, chromates, molybdates and tungstates)
System no. to Strunz
and to Dana
7.AD.05 ( 8th edition : VI / A.06)
02/28/01/02
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Pnam (No. 62, position 6)Template: room group / 62.6
Lattice parameters a  = 7.476  Å ; b  = 10.071 Å; c  = 5.763 Å
Formula units Z  = 4
Twinning cyclic twins according to {100}, {110} and {211}
Physical Properties
Mohs hardness 2
Density (g / cm 3 ) measured: 2.66; calculated: 2.667
Cleavage good after {010} and {001}
colour colorless, white, yellow
Line color White
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.494
n β  = 1.495
n γ  = 1.497
Birefringence δ = 0.004
Optical character biaxial positive
Axis angle 2V = 67 ° (measured); 70 ° (calculated)
Other properties
Chemical behavior water soluble

Arcanite is a rarely occurring mineral from the mineral class of "sulphates (selenates, tellurates, chromates, molybdates and tungstates)" with the chemical composition K 2 [SO 4 ] and thus chemically pure potassium sulphate .

Arcanite crystallizes in the orthorhombic crystal system and usually develops cyclic crystal twins from six individuals each with a thin, pseudo-hexagonal habit of up to one centimeter in size with a glass-like sheen on the surfaces, but is also found in the form of crusty coatings.

In its pure form, arcanite is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also be translucent white and take on a yellow color due to foreign admixtures.

Etymology and history

Potassium sulfate was already known in the Middle Ages . The Dutch alchemist Isaac Hollandus from the 14th century shows in his writings how potassium sulfate can be obtained from the residues of the distillation of the septic water ( nitric acid ) by heating saltpeter and iron vitriol . Based on the belief at the time that potassium sulfate emerged from the union of two salts, this new salt was given appropriate names such as Arcanum duplicatum , Panacea duplicata and Sal duplicatum ( Latin for "(ver) double secret", "(ver) double panacea "Or" double salt "). Paracelsus was already using potassium sulfate in medicine under the name Specificum purgans Paracelsi at the beginning of the 16th century , but it did not appear in the Prague drug tax until 1659. The synthesis of the compound was first achieved by Johann Rudolph Glauber (1604–1670), who called it Nitrum vitreolatum .

Potassium sulphate was first described as a natural mineral formation in 1832 by François Sulpice Beudant and referred to as aphthalosis (from ancient Greek αφθιτος for unchangeable and ἄλος for salt), since the slightly bitter, white salt does not change or transform in the air. He also mentions that synthetically crystallized aphthalose often shows bipyramidal dodecahedra, whereas the naturally formed mineral forms wart-shaped deposits in lava caves on Vesuvius .

The name Arcanit, which is still valid today, was coined in 1845 by Wilhelm von Haidinger , who, when choosing the name, referred to the original and therefore older name Arcanum duplicatum .

Occasionally, when the mineral is mentioned, the spelling arcanite is also found , whereby this name was also regarded as a synonym for aphthitalite (formerly glaserite ).

However, the type locality for the arcanite is the Santa Ana tin mine in the area of ​​the Californian settlement Trabuco Canyon , where the mineral was discovered by Norman E. Smith. Based on these samples, the complete first description was made in 1908 by Arthur Starr Eakle .

Since arcanite was known long before the International Mineralogical Association (IMA) was founded in 1958, it is recognized as a so-called grandfathered mineral as an independent mineral type.

The type material of the mineral is available at the University of California in Berkeley (California) and at Harvard University in Cambridge (Massachusetts) under catalog no. 100763 kept.

classification

In the outdated 8th edition of the mineral systematics according to Strunz , the arcanite belonged to the mineral class of "sulfates, chromates, molybdates, tungstates" (including some selenates and tellurates) and there to the department of "anhydrous sulfates without foreign anions ", where it together with Mascagnin the "Arcanit series" with the system no. VI / A.06 .

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.07-20 . In the “Lapis system” this also corresponds to the section “Anhydrous sulfates [SO 4 ] 2- , without foreign anions”, where arcanite, together with mascagnin and thénardite, forms an independent but unnamed group.

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 arcanite in 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 only large cations”, where it is only together with Mascagnin the “Arcanite group” with system no. 7.AD.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the arcanite to the class of "sulfates, chromates and molybdates" (including selenates, tellurates, selenites, tellurites and sulfites) and there in the "sulfates" category. Here he can also be found together with Mascagnin in the unnamed group 02/28/01 within the sub-section “ Anhydrous acids and sulfates (A + ) 2 XO 4 ”.

Chemism

Arcanite (K 2 SO 4 ) consists of 44.87% by weight of potassium (K), 18.40% by weight of sulfur (S) and 36.73% by weight of oxygen (O) or, expressed in oxide form, of 54 , 05% K 2 O and 45.95% SO 3 .

With Mascagnin (NH 4 ) 2 [SO 4 ], Arcanit forms a seamless series of mixed crystals .

Crystal structure

Arcanite crystallizes orthorhombically in the space group Pnam (space group no. 62, position 6) with the lattice parameters a  = 7.476  Å ; b  = & nbsp10.071 Å and c  = 5.763 Å as well as 4 formula units per unit cell . Template: room group / 62.6

The crystal structure of Arcanit consists of chains of edge- and surface-associated K [9] - and K [10] - polyhedra parallel to the c-axis [001]. These are carried SO 4 - tetrahedra and form together a pseudohexagonales backbone.

Crystal structure of arcanite
Color table: __ K     __ S     __ O

properties

Arcanite is very stable in air. However, like most sulfates , it is easily soluble in water. In ethanol ( alcohol ) and glycerin contrary, it is insoluble and also in alcohol it dissolves only in proportion to the water content.

Modifications and varieties

Taylorite has been an ammonium-containing variety of Arcanite with the formula (K, NH 4 ) 2 SO 4 since 1985 . The variety was named in 1892 by James Dwight Dana after WJ Taylor (1833–1864), a mineral chemist from Philadelphia, who briefly described the mineral in 1859 as the “sulfate of potassium and ammonium” from the guano deposits of the Chincha Islands off the Peruvian coast .

Due to the mixed crystal formation between arcanite and mascagnin, taylorite can also be viewed as an intermediate link in this series with a dominant potassium content.

Education and Locations

Arcanite was found near the type locality of the Santa Ana tin mine

Some small yellowish plates of a mineral that Mr. Norman E. Smith had sent to the author for identification were found to be natural potassium sulfate. They came from the Santa Ana Tin Mining Company's # 1 Tunnel in Trabuco Canon, Orange County, and were found about two hundred and fifty feet below the surface in an old Oregon Pine that is partially submerged six months a year. The tunnel is made of black shale that has some sulfide on it, and the walls of the mine are coated with tiny crystals and incrustations of sulfates and carbonates. Potassium sulfate has not yet been recognized as a mineral species, so this occurrence is classified as a new mineral.

In Italy, arcanite was discovered as a hydrothermal formation and associated with syngenite in rock samples from geothermal borehole no. 8 of the Cesano geothermal field (Italian: Campo geotermico di Cesano ) near Lake Bracciano . Furthermore, the mineral can arise as a conversion product from bird or bat guano, such as in the “Dingo Donga” cave near Madura and the “Murra-el-elevyn” cave near Cocklebiddy in Western Australia , the “Lobatse” caves near the place of the same name in Botswana.

As a rare mineral formation, arcanite could only be detected at a few sites, with around 30 sites being documented so far (as of 2019).

The only known find spot in Germany so far are the colored stone sand rocks below the Falkenburg near Wilgartswiesen in the Rhineland-Palatinate district of Südwestpfalz. The mineralogist Gerhard Frenzel discovered the mineral in 1964 in the sporadic efflorescence of salt minerals.

Other previously known sites are in Chile, France, Iran, Japan, Canada, Mexico, Namibia, Peru, Russia, Saudi Arabia, Spain, South Africa and other places in the United States of America.

See also

literature

  • FS Beudant : Traité élémentaire de minéralogie . 2nd Edition. tape 2 . Chez Verdière Libraire-Éditeur, Paris 1932, p. 477–478 (French, limited preview in Google Book search).
  • Wilhelm Haidinger : Handbook of determining mineralogy . Braumüller & Seidel, Vienna 1845, p. 470 ( available online at rruff.info [PDF; 311 kB ; accessed on March 20, 2019]).
  • Wilhelm Haidinger : Handbook of determining mineralogy . Braumüller & Seidel, Vienna 1845, p. 492 ( available online at rruff.info [PDF; 332 kB ; accessed on March 20, 2019] First Class: Akrogenide. IV. Order. Salts. XIII. Picrocholine salt. Arcanite).
  • Arthur S. Eakle: Notes on some California minerals . In: Bulletin of the Department of Geology . tape 5 , no. 14 , 1908, pp. 232 (English, available online at archive.org  - Internet Archive [accessed March 24, 2019] V. Arcanite from Orange County).
  • Clifford Frondel : Notes on arcanite, ammonian aphthitalite and oxammite . In: American Mineralogist . tape 35 , 1950, pp. 596–598 (English, available online at rruff.info [PDF; 207 kB ; accessed on March 20, 2019]).
  • John A. McGinnety: Redetermination of the structures of potassium sulphate and potassium chromate: the effect of electrostatic crystal forces upon observed bond length . In: Acta Crystallographica . B28, 1972, p. 2845–2852 , doi : 10.1107 / S0567740872007022 (English).

Web links

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

Individual evidence

  1. a b c Wilhelm Haidinger : Handbook of determining mineralogy . Braumüller & Seidel, Vienna 1845, p.  492 ( available online at rruff.info [PDF; 332 kB ; accessed on March 20, 2019] First Class: Akrogenide. IV. Order. Salts. XIII. Picrocholine salt. Arcanite).
  2. a b c d e Stefan Weiss: The great 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 .
  3. ^ A b 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.  367 (English).
  4. a b c d John A. McGinnety: Redetermination of the structures of potassium sulphate and potassium chromate: the effect of electrostatic crystal forces upon observed bond length . In: Acta Crystallographica . B28, 1972, p. 2845–2852 , doi : 10.1107 / S0567740872007022 (English).
  5. 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 .
  6. ^ A b c David Barthelmy: Arcanite Mineral Data. In: webmineral.com. Retrieved March 22, 2019 .
  7. a b c d Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York et al. 1997, ISBN 0-471-19310-0 , pp. 569 .
  8. a b c d Arcanite . 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; 68  kB ; accessed on March 19, 2019]).
  9. a b c d e Arcanite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 22, 2019 .
  10. a b c FA Flückiger: Pharmaceutische Chemie . 2nd, revised edition. First part. R. Gaertner's Verlag, Berlin 1888, p. 363–365 ( available online at archive.org  - Internet Archive [accessed March 25, 2019]).
  11. Gustav Fester: The development of chemical technology up to the beginnings of large-scale industry . Sendet, Wiesbaden 1969, p. 156 ( limited preview in Google Book search).
  12. Entry on potassium sulfate. In: Römpp Online . Georg Thieme Verlag, accessed on March 24, 2019.
  13. ^ FS Beudant : Traité élémentaire de minéralogie . 2nd Edition. tape  2 . Chez Verdière Libraire-Éditeur, Paris 1932, p. 477–478 (French, limited preview in Google Book search).
  14. ^ Wilhelm Haidinger : Handbook of determining mineralogy . Braumüller & Seidel, Vienna 1845, p.  470 ( available online at rruff.info [PDF; 311 kB ; accessed on March 20, 2019]).
  15. Chemicals Lexicon - Potassium Sulphate. In: chemischemlexikon.de. June 10, 2001, accessed March 24, 2019 .
  16. ^ Potash sulfuric acid. in: Meyers Großes Konversationslexikon
  17. Sulphates, chromium, molybdenum, tungsten, uranium, haloid salts and salt deposits . In: C. Doelter, H. Leitmeier (Hrsg.): Handbuch der Mineralchemie . Volume IV, Part Two. Springer, Berlin, Heidelberg 1929, p.  165 ( limited preview in Google Book search).
  18. Arthur S. Eakle: Notes on some California minerals . In: Bulletin of the Department of Geology . tape 5 , no. 14 , 1908, pp. 232 (English, available online at archive.org  - Internet Archive [accessed March 24, 2019] V. Arcanite from Orange County).
  19. Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: November 2018. (PDF 1753 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, November 2018, accessed on March 19, 2019 (English, Arcanite see p. 11).
  20. Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed October 2, 2019 .
  21. ^ Lee A. Groat, Frank C. Hawthorne: Taylorite discredited (= ammonian arcanite) . In: The Canadian Mineralogist . tape 23 , no. 2 , 1985, pp. 259–260 (English, brief description available online at pubs.geoscienceworld.org [accessed on March 22, 2019]).
  22. Taylorite (of Dana). In: mindat.org. Hudson Institute of Mineralogy, accessed March 22, 2019 .
  23. Clifford Frondel : Notes on arcanite, ammonian aphthitalite and oxammite . In: American Mineralogist . tape  35 , 1950, pp. 596–598 (English, available online at rruff.info [PDF; 207 kB ; accessed on March 20, 2019]).
  24. Localities for Arcanite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 22, 2019 .
  25. Find location list for arcanite at the Mineralienatlas and at Mindat