Padmait

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Padmait
General and classification
other names

IMA 1990-048

chemical formula PdBiSe
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.EB.25
02.12.03.10
Crystallographic Data
Crystal system cubic
Crystal class ; symbol pentagon-icositetrahedral; 432
Space group P 4 1 32 (No. 213) or P 4 3 32 (No. 212)Template: room group / 213Template: room group / 212
Lattice parameters a  = 6.45  Å
Formula units Z  = 4
Physical Properties
Mohs hardness 3 to 4 ( VHN 20 = 260 to 272 kg / mm 2 )
Density (g / cm 3 ) calculated 9.86
Cleavage imperfect in two mutually perpendicular directions
colour light yellow, pink-yellow in incident light
Line color black
transparency opaque (opaque)
shine Metallic luster

Padmait is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts " with the chemical composition PdBiSe and thus, chemically speaking, palladium - bismuth - selenide . As close relatives of the sulfides, the selenides are placed in the same class.

Padmait crystallizes in the cubic crystal system , but has so far only been found in the form of isometric, irregular grains of up to 0.2 mm in diameter and as symplectic adhesions with palladium sulfides . The mineral, which is opaque in every form, shows a metallic sheen on the surfaces of the light yellow, in incident light also pinkish-yellow, grains . In contrast, its stroke color is black.

Etymology and history

Was discovered Padmait first time in the uranium - vanadium - deposit Srednyaya Padma of Velikaya Guba near the eponymous river Padma on Lake Onega in the peninsula Zaonezhie ( Russian Заонежский ) in the south of the Russian Federation belonging to the Republic of Karelia . It was first described in 1991 by YS Polekhovskij, AV Voloshin, IP Tarasova, SA Nikitin, YA Pakhomovskij, YP Men'shikov, YL Kretzer and TI Kolytscheva, who named the mineral after its type locality .

The type material of the mineral is kept in the Mining Museum of the State Mining University of Saint Petersburg (formerly Mining Institute ).

classification

Since the Padmait was only recognized as an independent mineral in 1990 and this was only published in 1991, it is not yet included in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . 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.17-175 . 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 Padmait together with Aurostibit , Cattierit , Changchengit , Dzharkenit , Erlichmanit , Fukuchilit , Geversit , Hauerit , Insizwait , Krutaite , Laurit , Maslovit , Mayingit , Michenerit , Penroseite , pyrite , Sperrylith , Testibiopalladit , Trogtalit , Vaesit and Villamanínit an independent, but unnamed group / the "pyrite group" with the system no. II / D.17 forms (as of 2018).

The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, classifies the padmait in the newly defined section 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 , Krutovit , Maslovit, Mayingit, Michenerit, Milotait , 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 the Padmait to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here it is in the " cobaltite group (cubic or pseudocubic crystals) " with the system no. 02.12.03 within the subsection "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 2".

Chemism

According to the ideal (theoretical) composition of Padmait (PdBiSe), the mineral consists of palladium (Pd), bismuth (Bi) and selenium (Se) in a molar ratio of 1: 1: 1. This corresponds to a mass fraction of 26.99% Pd, 52.99% Bi and 20.02% Se.

However, the values ​​from 30 microprobe analysis on nine samples of the type material showed an average composition of 25.70% Pd, 53.60% Bi and 18.80% Se as well as an additional low content of 1.20% platinum (Pt), 0.80 Silver (Ag) and 0.20% sulfur (S). Occasionally traces of gold (Au) could also be detected, but this value usually approached zero. The measured compositions correspond to the empirical formula Pd 0.96 Pt 0.02 Bi 1.02 Ag 0.03 Se 0.94 S 0.02 , which was idealized to PdBiSe.

Crystal structure

Padmait crystallizes cubically in the space group P 4 1 32 (space group no. 213) or P 4 3 32 (no. 212) with the lattice parameter a  = 6.45  Å and four formula units per unit cell . Template: room group / 213Template: room group / 212

Education and Locations

Padmait is found in metasomatic rocks that were formed in shungite-containing meta- schists of the lower Proterozoic . At its type locality Srednyaya Padma / Velikaya Guba in southern Karelia , the mineral occurs in paragenesis with Bohdanowiczit , Clausthalit , dolomite , Froodit , hematite , Paraguanajuatit , chromium-containing Phengite , quartz , roscoelite and Sobolevskit on and solid bismuth and gold.

Padmait is one of the very rare mineral formations that have so far only been known in a few samples. Its type locality is the only known site in Russia to date . The only other known locations are the Buraco do Ouro gold mine in the municipality of Cavalcante in the Brazilian state of Goiás and the Coldwell complex as the largest alkali complex in North America near Marathon in the Canadian province of Ontario (as of 2020).

See also

literature

  • Ю.С. Полеховский, д. чл. А. В. Волошин, И. П. Тарасова, С. А. Никитин, д. чл. Я. А. Пахомовский, д. чл. Ю. П. Меньшиков, Ю. Л. Крецер, Т. И. Колычева: Падмаит PdBiSe - Новый Селенид Палладия и Висмута из Метасоматитов Южной Карелии . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 120 , no. 3 , 1991, pp. 85–88 (Russian, rruff.info [PDF; 437 kB ; accessed on April 25, 2020] English translation: YS Polekhovskij, AV Voloshin, IP Tarasova, SA Nikitin, YA Pakhomovskij, YP Men'shikov, YL Kretzer, TI Kolytscheva: Padmaite PdBiSe - a new selenide of palladium and bismuth from metasomatites of the southern Karelia. ).
  • John Leslie Jambor , Jacek Puziewicz: New mineral names . In: American Mineralogist . tape 78 , 1993, p. 451–452 (English, rruff.info [PDF; 1.1 MB ; accessed on April 25, 2020]).
  • 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. 127 .
  • Igor V. Pekov: Minerals first discovered on the territory of the former Soviet Union . 1st edition. Ocean Pictures, Moscow 1998, ISBN 5-900395-16-2 , pp. 158, 526 .

Web links

  • Padmait. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on April 25, 2020 .
  • Padmaite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 25, 2020 .

Individual evidence

  1. ↑ a b c 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 April 25, 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.  105 (English).
  3. ^ A b c d e John Leslie Jambor , Jacek Puziewicz: New mineral names . In: American Mineralogist . tape  78 , 1993, p. 451 (English, rruff.info [PDF; 1.1 MB ; accessed on April 25, 2020]).
  4. ↑ a b c 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 .
  5. ↑ Catalog of Type Mineral Specimens - P. (PDF 113 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed April 25, 2020 .
  6. ^ The Depositories of Mineral Type Specimens - MM, St. Petersburg. Commission on Museums (IMA), 2002, accessed April 25, 2020 .
  7. ↑ 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 April 25, 2020 .
  8. ↑ Padmait. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on April 25, 2020 .
  9. ↑ David Barthelmy: Padmaite MineralData. In: webmineral.com. Retrieved April 24, 2020 (English).
  10. ↑ Ю.С. Полеховский, д. чл. А. В. Волошин, И. П. Тарасова, С. А. Никитин, д. чл. Я. А. Пахомовский, д. чл. Ю. П. Меньшиков, Ю. Л. Крецер, Т. И. Колычева: Падмаит PdBiSe - Новый Селенид Палладия и Висмута из Метасоматитов Южной Карелии . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 120 , no. 3 , 1991, pp. 87 (Russian, rruff.info [PDF; 437 kB ; accessed April 24, 2020] English translation: YS Polekhovskij, AV Voloshin, IP Tarasova, SA Nikitin, YA Pakhomovskij, YP Men'shikov, YL Kretzer, TI Kolytscheva: Padmaite PdBiSe - a new selenide of palladium and bismuth from metasomatites of the southern Karelia. ).
  11. ↑ Ю.С. Полеховский, д. чл. А. В. Волошин, И. П. Тарасова, С. А. Никитин, д. чл. Я. А. Пахомовский, д. чл. Ю. П. Меньшиков, Ю. Л. Крецер, Т. И. Колычева: Падмаит PdBiSe - Новый Селенид Палладия и Висмута из Метасоматитов Южной Карелии . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 120 , no. 3 , 1991, pp. 88 (Russian, rruff.info [PDF; 437 kB ; accessed April 24, 2020] English translation: YS Polekhovskij, AV Voloshin, IP Tarasova, SA Nikitin, YA Pakhomovskij, YP Men'shikov, YL Kretzer, TI Kolytscheva: Padmaite PdBiSe - a new selenide of palladium and bismuth from metasomatites of the southern Karelia. ).
  12. ↑ Find location list for Padmait at [Mineralienatlas] and at Mindat , accessed on April 25, 2020.