Euchlorin

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Euchlorin
Euchlorine-808836.jpg
Euchlorin from Vesuvius , Naples, Campania, Italy
General and classification
chemical formula
  • KNaCu 3 [O | (SO 4 ) 3 ]
  • KNaCu 3 O (SO 4 ) 3
Mineral class
(and possibly department) 		Sulphates, Selenates, Tellurates, Chromates, Molybdates and Wolframates
System no. to Strunz
and to Dana 		7.BC.30 ( 8th edition : VI / B.06)
03/30/01/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / c (No. 15)Template: room group / 15
Lattice parameters a  = 18.41  Å ; b  = 9.43 Å; c  = 14.21 Å
β  = 113.7 °
Formula units Z  = 8
Frequent crystal faces {001}
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) measured: 3.27; calculated: 3.28
Cleavage good in two directions
colour dark to light green, emerald to turquoise green
Line color pistachio green
transparency translucent
shine not defined
Crystal optics
Refractive indices n α  = 1.580
n β  = 1.605
n γ  = 1.644
Birefringence δ = 0.064
Optical character biaxial positive
Pleochroism Visible:
X = light
grass green Y = grass green
Z = bright yellow green
Other properties
Chemical behavior water soluble

Euchlorin is a very rarely occurring mineral from the mineral class of "sulfates, selenates, tellurates, chromates, molybdates and tungstates" (including selenates and tellurates) with the idealized chemical composition KNaCu 3 [O | (SO 4 ) 3 ] and is therefore chemical viewed potassium - sodium - copper - sulfate with additional oxygen ions .

Euchlorin crystallizes in the monoclinic crystal system and develops tabular crystals with a rectangular cross-section up to about two millimeters in size in the direction of the a-axis , but is mostly found in the form of crusty coatings . The mineral is translucent and has a dark emerald green to light turquoise green color with a pistachio green streak . A description of the surface gloss is missing so far.

Etymology and history

Euchlorin was discovered in 1869 by Arcangelo Scacchi after a volcanic eruption on the fumaroles of Vesuvius in the Italian region of Campania . The mineral was first described in 1884 by his son Eugenio in the Italian magazine Rendiconto dell'Accademia delle Scienze Fisiche e Matematiche , who named it after the Greek word εΰχλωρος (eukhlōros) for greenish, yellowish , based on its characteristic light green color . This in turn consists of εΰ (eu) for fine or beautiful and χλωρος (khlōros) for light green .

Euchlorin was known as Cu-Na-K-Sulphate, but an exact determination of the chemical composition was lacking. In 1989, F. Scordari, F. Stasi and A. De Marco carried out a new analysis of the mineral using a sample from the collection of the Mineralogical Museum of Naples (Italian: Real Museo Mineralogico ), which was labeled "Euchlorin from Vesuvius, 1880".

Due to the first description before the founding of the International Mineralogical Association (IMA) in 1958, the mineral is registered as a so-called grandfathered mineral (G), despite the exact composition that was only determined later .

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the Euchlorin belonged to the mineral class of "sulfates, chromates, molybdates and tungstates" (including selenates and tellurates) and there to the department of "anhydrous sulfates, with foreign anions " , where he was the only member of the unnamed group VI / B.06 .

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 Euchlorin to the category of “sulfates (selenates, etc.) with 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 it forms the unnamed group 7.BC.30 together with Fedotovite .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Euchlorin to the class of "sulfates, chromates and molybdates" (including selenates, tellurates, selenites, tellurites and sulfites) and there in the category of "anhydrous sulfates with hydroxyl or Halogen ”. Here he is the only member of the unnamed group 30.03.01 within the sub-section “ Anhydrous sulfates with hydroxyl or halogen with various formulas ”.

Chemism

Seven analysis with the electron - microprobe showed an average composition of 44.50% CuO , 8.41% K 2 O , 6.47% Na 2 O , 0.07% CaO , 0.17% MgO , 0.06% Al 2 O 3 , 42.18% SO 3 (Σ = 101.86 wt%). On the calculation basis of 100% by weight, the empirical formula Na 1.180 K 1.012 Ca 0.007 Mg 0.024 Cu 3.146 O 1.273 (SO 4 ) 3 was determined, which was idealized to NaKCu 3 O (SO 4 ) 3 .

In the idealized, theoretical composition, Euchlorin consists of 7.02% potassium (K), 4.13% sodium (Na), 34.23% copper (Cu), 17.27% sulfur (S) and 37.35% oxygen (O).

Crystal structure

Euchlorin crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a  = 18.41  Å ; b  = 9.43 Å; c  = 14.21 Å and β = 113.7 ° and 8 formula units per unit cell . Template: room group / 15

properties

Like most sulfates, Euchlorin is easily soluble in water.

There is no information about the Mohs hardness of Euchlorin or about the fracture behavior . The information on the cleavage of the mineral is also only known imprecisely and is described as good in two directions. The measured density for Euchlorin is 3.27 g / cm 3 and the calculated density is 3.28 g / cm 3 .

Education and Locations

Euchlorin is formed as a precipitate on fumaroles . At its type locality on Vesuvius , the sulfates dolerophanite and chalcocyanite as well as the chlorides eriochalcite and melanothallite appeared as accompanying minerals .

As a rare mineral formation, Euchlorin could only be detected at a few sites, with around 10 sites being documented so far (as of 2018). In Italy, apart from Vesuvius, the mineral was only found in the Atrio del Cavallo , the western part of the connecting valley Valle del Gigante between Vesuvius and Monte Somma .

At the fumaroles of the volcano Izalco in the department of Santa Ana in El Salvador to Euchlorin found associated with the first discovered there minerals Fingerit , Mcbirneyit , Stoiberit , Thenardite and Ziesit .

The volcano Tolbachik and its northern break with his first and second cinder cone on the peninsula of Kamchatka in Russia's Far East, the mineral stepped addition to those already mentioned, you still together with copper- Anglesite , Fedotovit , dignified gold , Tenorite and Vergasovait on.

Furthermore, one knows Euchlorin yet from the burning coal - heaps of pit Marcel in Radlin in Rybnik area in the Polish province of Silesia .

See also

literature

  • Eugenio Scacchi: Sull 'euclorina, sull' eriocaleo e sul melanotallo . In: Rendiconto dell'Accademia delle Scienze Fisiche e Matematiche . tape 23 , 1884, p. 158–165 (Italian, rruff.info [PDF; 776 kB ; accessed on October 10, 2018]).
  • F. Scordari, F. Stasi, A. De Marco: Euchlorin: New crystallographic and chemical data . In: New yearbook for mineralogy, monthly books . tape 3 , 1989, pp. 541-550 (English).
  • John L. Jambor , Jazec Puziewicz: New Mineral Names . In: American Mineralogist . tape 75 , 1990, pp. 1209–1216 (English, rruff.info [PDF; accessed on October 11, 2018] Euchlorine p. 1214).
  • F. Scordari, F. Stasi: The crystal structure of euchlorine, NaKCu 3 O (SO 4 ) 3 . In: New Yearbook for Mineralogy, Treatises . tape 161 , 1990, pp. 241-253 (English).
  • 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. 637 (English).

Web links

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

Individual evidence

  1. ↑ a b c d 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.  275 (English).
  2. ↑ a b IMA / CNMNC List of Mineral Names; September 2018 (English, PDF 1.7 MB)
  3. ↑ a b Webmineral - Euchlorine (English).
  4. ↑ a b c d e f g Euchlorine . 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; 66  kB ; accessed on October 11, 2018]).
  5. ↑ a b Marco E. Ciriotti, Lorenza Fascio, Marco Pasero: Italian Type Minerals . 1st edition. Edizioni Plus - Università di Pisa, Pisa 2009, ISBN 978-88-8492-592-3 , p. 115 .
  6. ↑ 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 .
  7. ↑ a b c d e f Mindat - Euchlorine (English).
  8. ^ Homepage of the Real Museo Mineralogico (Italian).
  9. ^ A b John L. Jambor , Jazec Puziewicz: New Mineral Names . In: American Mineralogist . tape  75 , 1990, pp. 1209–1216 (English, rruff.info [PDF; accessed on October 11, 2018] Euchlorine p. 1214).
  10. ↑ Mindat - Number of locations for Euchlorine (English).
  11. ↑ Find location list for Euchlorin in the Mineralienatlas and Mindat .