Švenekit
| Švenekit | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Ca [AsO 2 (OH) 2 ] 2 |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.AD.10 01.37.07.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 8.5606 (5) Å ; b = 7.6926 (6) Å; c = 5.7206 (4) Å α = 92.605 (6) °; β = 109.9002 (6) °; γ = 109.9017 (6) ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | ≈ 2 |
| Density (g / cm 3 ) | measured: 3.16 (1); calculated: 3.26 |
| Cleavage | very good after {010} |
| Break ; Tenacity | uneven; brittle |
| colour | colorless, chalk white |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.602 (2) n γ = 1.658 (2) |
| Birefringence | δ = 0.056 |
| Optical character | biaxial |
Švenekit is a very rarely occurring minerals from the mineral class of "phosphates, arsenates, and vanadates" with the chemical composition Ca [AsO 2 (OH) 2 ] 2 , and thus chemical point of a basic calcium - arsenate .
Švenekit crystallizes in the triclinic crystal system , but develops only microscopic, platelet-shaped crystals up to about 100–150 μm in length, which are usually fused together to form rosette-shaped mineral aggregates up to about 3 mm in diameter. You can also find Švenekit in the form of grape crusts.
In its pure form, Švenekit is colorless and transparent with a glass-like sheen on the surfaces. However, due to multiple refraction due to lattice construction defects or polycrystalline training, it can also be translucent as chalk white.
Etymology and history
Švenekit was discovered for the first time in the slip passage of the Einigkeit mine near the Czech town of Jáchymov . The analysis and first description of the took place in 1999 by a team of mineralogists around Petr Ondruš, namely Roman Skála, Jakub Plášil, Jiří Sejkora, František Veselovsky, Jiří Čejka, Anna Kallistova, Jan Hloušek, Karla Fejfarová, Radek Šková, Michal Dušek, Ananda, Vladimír Machovič and Ladislav Lapčák. They named the mineral in honor of Jaroslav Švenek (1927–1994), the former curator of the mineralogical collection in the Prague National Museum .
The analysis results and the chosen name were submitted to the International Mineralogical Association (IMA) for examination (internal entry number of IMA: 1999-007 ), which recognized Švenekit as an independent mineral species. The first description was published in 2013 in Mineralogical Magazine .
Occasionally, the mineral name can be found in the spelling Svenekit (without Hatschek above the S), which does not, however, correspond to the specifications for mineral naming of the IMA, according to which, for example, minerals that have been named after a person must be spelled the name is adopted. The inconsistent spelling of their names for many minerals was corrected with the publication Tidying up Mineral Names: an IMA-CNMNC Scheme for Suffixes, Hyphens and Diacritical marks in 2008, and the Švenekit has been spelled internationally since then with the associated acute.
The type material of the mineral is also in the Prague National Museum under catalog no. P1p 2/99 kept.
classification
Since the Švenekit was only recognized as an independent mineral in 1999, it is not yet listed in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . Only in the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which is still based on this form of Karl Hugo Strunz's systematic out of consideration for private collectors and institutional collections , the mineral received the system and mineral number. VII / A.12-25 . In the "Lapis system" this corresponds to the class of "phosphates, arsenates and vanadates" and there the section "Anhydrous phosphates [PO 4 ] 3− , without foreign anions ", where Švenekit together with archerite , bario-olgite , biphosphammite , Buchwaldit , Iwateit , monetite , Nahpoit , Olgit , Phosphammit and Weilit forms a separate, but unnamed group.
The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also assigns the Švenekit to the category of “phosphates 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 Monetite and Weilite the “Monetite group” with the System no. 8.AD.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Švenekit to the class of "phosphates, arsenates and vanadates" and there in the department of "phosphate minerals". Here he is to be found as the only member of the unnamed group 01/37/07 within the sub-section “Anhydrous acid phosphates etc., with various formulas”.
Crystal structure
Švenekite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a = 8.5606 (5) Å ; b = 7.6926 (6) Å; c = 5.7206 (4) Å; α = 92.605 (6) °; β = 109.9002 (6) ° and γ = 109.9017 (6) ° as well as two formula units per unit cell .
Education and Locations
Švenekit formed secondarily near polymetallic hydrothermal - veins . Possible mineral parageneses were not named, but the type locality Grube Einigkeit or the Geschieber-Gang named in the original description is rich in mineral finds. For example, in addition to the Švenekit with Adolfpaterait , Běhounekit , Geschieberit , Ježekit , Línekit , Mathesiusit , Ondrušit , Slavkovit , Štěpit and Vysokýit , 10 other minerals were discovered for the first time (status 2018).
Apart from its type locality Grube Einigkeit and Geschieber-Gang, no other sites are known for the Švenekit.
See also
literature
- G. Ferraris, DW Jones and J. Yerkess: A neutron diffraction study of the crystal structure of calcium bis (dihydrogen arsenate), Ca (H 2 AsO 4 ) 2 . In: Acta Crystallographica . B 28, 1972, p. 2430-2437 , doi : 10.1107 / S0567740872006247 .
- Petr Ondruš, novel Skala, Jakub Plášil, Jiri Sejkora, Frantisek Veselovsky, Jiri Čejka, Anna Kallistova, Jan Hloušek, Karla Fejfarová, Radek Skoda, Michal Dusek, Ananda Gabašová, Vladimir Machovič, Ladislav Lapčák: Švenekite, Ca [AsO 2 (OH ) 2 ] 2 , a new mineral from Jáchymov, Czech Republic . In: Mineralogical Magazine . tape 77 , no. 6 , 2013, p. 2711–2724 , doi : 10.1180 / minmag.2013.077.6.02 .
- Dmitriy I. Belakovskiy, Fernando Cámara, Olivier C. Gagne, Yulia Uvarova: New Mineral Names . In: American Mineralogist . tape 100 , 2015, p. 2352–2362 ( rruff.info [PDF; 423 kB ; accessed on December 8, 2019]).
Web links
- Mineral Atlas : Švenekit (Svenekit) (Wiki)
- David Barthelmy: Svenekite Mineral Data. In: webmineral.com. (English).
- American-Mineralogist-Crystal-Structure-Database - Švenekite. In: rruff.geo.arizona.edu. (English).
Individual evidence
- ↑ a b c Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: November 2019. (PDF 1720 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, November 2019, accessed December 8, 2019 .
- ↑ a b c d 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 .
- ↑ a b c Petr Ondruš, Roman Skala, Jakub Plášil, Jiří Sejkora, František Veselovsky, Jiří Čejka, Anna Kallistova, Jan Hloušek, Karla Fejfarová, Radek Škoda, Michal Dušek, Ananda Gabašová, Vladimír Machovič, Ladislav Lapčák: Švenekite, Ca [ AsO 2 (OH) 2 ] 2 , a new mineral from Jachymov, Czech Republic . In: Mineralogical Magazine . tape 77 , no. 6 , 2013, p. 2711–2724 , doi : 10.1180 / minmag.2013.077.6.02 .
- ↑ a b c d Svenekite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 291 kB ; accessed on December 8, 2019]).
- ↑ a b c d Švenekite. In: mindat.org. Hudson Institute of Mineralogy, accessed December 8, 2019 .
- ↑ 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. 8 and following (English, cnmnc.main.jp [PDF; 316 kB ; accessed on December 8, 2019]).
- ^ 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 ( cnmnc.main.jp [PDF; 2.4 MB ; accessed on December 8, 2019]).
- ↑ a b Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed December 8, 2019 .
- ↑ Type locality Geschieber-Gang in the Mineralienatlas and Mindat , accessed on December 8, 2019.
- ↑ List of locations for Švenekite in the Mineralienatlas and Mindat , accessed on December 8, 2019.