Krutovit

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Krutovit
Krutovite-831017.jpg
Krutovite crystal (light gray) in a matrix from Jáchymov , Czech Republic
( total size of the sample 5.6 cm × 4.9 cm × 3.2 cm )
General and classification
other names

IMA 1975-009

chemical formula NiAs 2
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.EB.25
02.12.01.12
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  = 5.79  Å
Formula units Z  = 4
Physical Properties
Mohs hardness 5.5
Density (g / cm 3 ) calculated: 7.08 to 7.12
Cleavage not defined
colour light gray to off-white
Line color not defined
transparency opaque (opaque)
shine Metallic luster

Krutovite is a very rare mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition NiAs 2 and thus, chemically speaking, nickel diarsenide .

Krutovite crystallizes in the cubic crystal system , but has so far only been found in the form of tiny grains up to about 0.1 mm in size or closely intergrown with other sulfide minerals. The mineral is in any form opaque ( opaque ) and displays on the surfaces of light gray to gray white grains have a metallic luster .

Etymology and history

The synthetic compound NiAs 2 was prepared and analyzed in 1968 by Ronald A. Munson. According to his analyzes, nickel diarsenide crystallizes cubically in the pyrite structure . In the same year, Hans Holseth and Arne Kjekshus also analyzed several compounds with a molar ratio of M: X 2 and determined an orthorhombic symmetry for the compound β-NiAs 2 . According to the lattice parameters determined by Holseth and Kjekshus, β-NiAs 2 is identical to the mineral rammelsbergite .

In 1970 P. Kašpar and K. Paděra described a gersdorffite with unusually large cell parameters, which should come from the Potůčky deposit . However, it was only after their publication that it was established that the type locality was not the Potůčky deposit near the village of the same name (German Breitenbach ), as stated , but the "Geshiber-Gang" (actually Geschieber-Gang ) in the former Einigkeit mine near Jáchymov (German Sankt Joachimsthal ) is in the Czech region of Karlovy Vary (German Karlsbad ).

After a detailed analysis of the composition and structure of the unusual Gersdorffite, RA Vinogradova, NS Budashevskiy, IA Bud'ko, LI Bochek, P. Kāspar and K. Paděra determined that it was a cubic nickel diarsenide and thus a previously unknown mineral. They named the newly discovered mineral after the former professor of mineralogy at Moscow State University Georgy Alekseevich Krutov (Russian: Георгий Алексеевич Крутов, 1902-1989).

The test results and the chosen name were submitted to the International Mineralogical Association (IMA) for examination in 1975 (internal entry no .: 1975-009), which Krutovit recognized as an independent mineral species. The recognition was published in 1977 in the American Mineralogist magazine .

Type material of the mineral is in the National Museum of Prague in the Czech Republic under catalog no. 61625 as well as in the Mining Institute in Saint Petersburg and in the Fersman Museum of the Russian Academy of Sciences in Moscow , Russia.

classification

Since the krutovite was only recognized as an independent mineral in 1975 and this was only published in 1977, it is not yet included in the 8th edition of the mineral classification according to Strunz , which was last updated in the same year . Only in the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , was the mineral given the system and mineral number. II / D.19-10 . In the "Lapis system" this corresponds to the class of "sulfides and sulfosalts" and there the section "sulfides with [the molar ratio] metal: S, Se, Te <1: 1", where Krutovit is the only member of the unnamed group II /D.19 forms (as of 2018).

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and was updated by the IMA until 2009, classifies the krutovite in the newly defined division of “metal sulfides with a molar ratio of M: S ≤ 1: 2”. This is further subdivided according to the exact molar ratio and the predominant metals in the compound, so that the mineral can be found in the sub-section "M: S = 1: 2, with Fe, Co, Ni, PGE etc." according to its composition where it together with Changchengit, Cobaltit , Gersdorffit-P213 , Gersdorffit-Pa3 , Gersdorffit-Pca21 , Hollingworthit , Irarsit , Jolliffeit , Kalungait , Maslovit, Mayingit , Michenerit, Milotait , Padmait, Platarsit , Testibiopalladit, Tolovkit , Ullmannit and Willyamit the " Gersdorffitgruppe "with the system no. 2.EB.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns krutovite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here, however, it is in the " pyrite group (isometric: Pa3) " with the system no. 02.12.01 to be found within the subsection “Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2”.

Chemism

The idealized (theoretical) composition of Krutovite (NiAs 2 ) consists of nickel (Ni) and arsenic (As) with a molar ratio of 1: 2, which gives a mass fraction (% by weight) of 28.15% Ni and 71.85% As equals.

The results of the 32 microprobe analyzes on the type material from Krutovit from Jáchymov, however, showed a slightly different composition of an average of 24.98% Ni and 73.37% As as well as additional low contents of 0.86% copper (Cu), 0.22% cobalt ( Co), 0.15% iron (Fe) and 0.19% sulfur (S). On the basis of two arsenic atoms, the values ​​correspond to the empirical composition (Ni 0.7 Cu 0.03 Co 0.01 ) Σ = 0.91 As 2.00 .

Crystal structure

Krutovit crystallizes cubically in the space group P 2 1 3 (space group no. 198) with the lattice parameter a  = 5.79  Å and four formula units per unit cell . Template: room group / 198

properties

Krutovit is resistant to potassium hydroxide (KOH) as well as hydrochloric acid (HCl), iron (III) chloride (FeCl 3 ) and mercury (II) chloride (HgCl 2 ). Surfaces etched with 50% nitric acid turn dark brownish-gray with iridescent edges.

Normally Krutovit is light gray to gray-white in color and lighter than the often with him socialized Minerals Nickelskutterudit . On polished surfaces, the color of Krutovit turns into a light white with a pink tinge.

Modifications and varieties

The compound NiAs 2 is trimorphic and occurs in nature in addition to the cubic crystallizing krutovite (α-NiAs 2 ) as orthorhombically crystallizing rammelsbergite (β-NiAs 2 ) and also as orthorhombic, but in a different space group crystallizing pararammelsbergite .

Education and Locations

Gray-metallic krutovite aggregate with green nickel silicates and some quartz from the Teliatko-serpentinite ore body, Dobšiná, Slovakia (field of view 1.2 cm)

Krutovite is formed by hydrothermal processes in Co-Ni-As-containing sulphide tunnels . At its type locality, the Geschieber-Gang near Jáchymov in the Czech Republic, tennantite appeared as an accompanying mineral in addition to nickel cutterudite . Other accompanying minerals from the Ni-Co deposit Khovu-Aksy with arsenides in carbonate dikes in the Republic of Tuwa in the Russian federation of Siberia are also known as Breithauptite , Löllingite , Nickelin , Rammelsbergite and Pararammelsbergite as well as solid silver .

Krutovit is one of the very rare mineral formations that has so far only been discovered in a few mineral samples from 13 documented locations (as of 2020). The Geschieber speed in the pit agreement and the deposit Potůčky in the district of Karlsbad ( Karlovy Vary are) while the previously known localities in the Czech Republic .

The only known locality in Germany in 1974 abandoned and largely flooded diorite - quarry on Wingertsberg in Nieder-Ramstadt in southern Hesse Mühltal community. In addition to bismuth, silver, cobalt and nickel ores, uranium ores such as uraninite and the rare uranium minerals zeunerite and metazeunerite were discovered here in the 1960s .

In Switzerland, too, the former Grand-Praz mine with its Cu-Ni-Bi-As mineralization near Ayer (Val d'Anniviers) in the canton of Valais is only one known site for krutovite.

Other previously known sites are the Maracás Menchen Mine in the municipality of the same name in the Brazilian state of Bahia , the deposits Belorechensk near Maikop (Republic of Adygeja ), Ishkinino near Gai (English Gay , Orenburg Oblast) and Khovu-Aksy near Chedi-Kholky (Republic of Tuva ) in Russia as well as the serpentine , ultra- basic Teliatko ore bodies and the hydrothermal quartz-carbonate vein system Zemberg-Terézia in the mining district Dobšiná (German Dobschau ) in the (Košický kraj) and the former gold and silver mining area Vyšná Boca (Žilinský kraj) in Slovakia.

See also

literature

  • Ronald A. Munson: The synthesis of iridium disulfide and nickel diarsenide having the pyrite structure . In: Inorganic Chemistry . tape 7 , no. 2 , 1968, p. 389-390 , doi : 10.1021 / ic50060a047 (English).
  • Д. Члены Р., А. Виноградова, Н. С. Рудашевский, И. А. Будько, Л. И. Бочек П. Кашпар, К. Падера: Крутовит - Новый Кубический Диарсенид Никеля . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 105 , no. 1 , 1976, p. 59–71 (Russian, rruff.info [PDF; 1,3 MB ; accessed on June 5, 2020] English translation: RA Vinogradova, NS Rudashevskii, IA Budko, LI Bochek, P. Kaspar, K. Padera: Krutovite, a new cubic nickel diarsenide ).
  • RA Vinogradova, NS Budashevskiy, IA Bud'ko, LI Bochek, P. Kāspar, K. Paděra: Krutovite, a new cubic nickel diarsenide . In: International Geology Review . tape 19 , 1977, pp. 232–244 , doi : 10.1080 / 00206817709471017 (English).
  • Martin Števko, Jiří Sejkora, Jiří Litochleb, Ivo Macek, Peter Bačík: Krutovit a sprievodné minerály z lokality Dobšiná-Teliatko (Slovenská republika) . In: Bulletin Mineralogie Petrology . tape 21 , no. 1 , 2013, p. 1–14 (Slovak, bullmineral.cz [PDF; 5.3 MB ; accessed on June 5, 2020] Brief description in English: Krutovite and associated minerals from the Dobšiná-Teliatko occurrence (Slovak Republic) ).

Web links

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

Individual evidence

  1. ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed June 11, 2020 .
  2. ↑ 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.  106 (English).
  3. ↑ a b c d e f Krutovite . 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; 63  kB ; accessed on June 11, 2020]).
  4. ^ A b c Michael Fleischer , Joseph Anthony Mandarino : New mineral names . In: American Mineralogist . tape  62 , 1977, pp. 173–176 (English, rruff.info [PDF; 430 kB ; accessed on June 11, 2020]).
  5. ↑ Ronald A. Munson: The synthesis of iridium disulfide and nickel diarsenide having the pyrite structure . In: Inorganic Chemistry . tape 7 , no. 2 , 1968, p. 389-390 , doi : 10.1021 / ic50060a047 (English).
  6. ↑ Hans Holseth, Arne Kjekshus: Compounds with the Marcasite Type Crystal Structure. I. Compositions of the Binary Pnictides . In: Acta Chemica Scandinavica . tape 22 , 1968, p. 3273–3283 , doi : 10.3891 / acta.chem.scand.22-3273 (English, actachemscand.org [PDF; 1,2 MB ; accessed on June 11, 2020]).
  7. ↑ RA Vinogradova, NS Budashevskiy, IA Bud'ko, LI Bochek, P. Kaspar, K. Padera: Krutovite, a new cubic nickel diarsenide . In: International Geology Review . tape 19 , 1977, pp. 232–244 , doi : 10.1080 / 00206817709471017 (English).
  8. ↑ Catalog of Type Mineral Specimens - K. (PDF 96 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed June 11, 2020 .
  9. ↑ 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 .
  10. ↑ Ernest H. Nickel , Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed June 11, 2020 .
  11. ↑ Krutovit. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on June 11, 2020 .
  12. ↑ Localities for Krutovite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 11, 2020 .
  13. ↑ Find location list for Krutovit in the Mineralienatlas and Mindat , accessed on June 11, 2020.