Polydymite

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Polydymite
Polydymite-614287.jpg
Polydymite from the Grüneau mine near Schutzbach , Siegerland, Rhineland-Palatinate
(field of view: 2.4 mm)
General and classification
other names

Trine tetrasulfide

chemical formula Ni 2+ Ni 3+ 2 S 4
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.DA.05 ( 8th edition : II / C.01)
02.10.01.07
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fd 3 m (No. 227)Template: room group / 227
Lattice parameters a  = 9.47  Å
Formula units Z  = 8
Twinning after {111}
Physical Properties
Mohs hardness 4.5 to 5.5 ( VHN 100 = 379 to 427)
Density (g / cm 3 ) measured: 4.5 to 4.8; calculated: 4.83
Cleavage imperfect after {001}; also observed after {111}
Break ; Tenacity uneven to scalloped
colour light gray to steel gray, tapering copper red
Line color blackish gray to black
transparency opaque (opaque)
shine Metallic luster

Polydymite is a rather seldom occurring mineral from the mineral class of " sulphides and sulphosalts " with the chemical composition Ni 2+ Ni 3+ 2 S 4 and thus, chemically speaking, trin nickel tetrasulphide . Structurally, however, polydymite belongs to the group of spinels .

Polydymite crystallizes in the cubic crystal system and develops mostly octahedral crystals and twins of up to one centimeter in size, but is also found in the form of granular to massive mineral aggregates . The mineral is always opaque and shows a metallic sheen on the surfaces of the light gray to steel gray crystals . In fresh mineral samples, the metallic luster is extremely brilliant. Since polydymite can turn copper-red over time in the air, the gloss also weakens. The line color of polydymite, on the other hand, is blackish gray to black.

With Linneit (Co 2+ Co 3+ 2 S 4 ), polydymite forms a continuous mixed crystal row .

Etymology and history

When investigating a mineral sample from siderite (mined: siderite ) and quartz with no place of origin, which in the mineral collection of the Aachen RWTH was issued, fell Hugo Laspeyres some very well-developed and to large to five millimeters, polysynthetic octahedron -Zwillinge a light-gray ore under Milleritnadeln on. The qualitative analysis showed that it was a previously unknown compound consisting mainly of nickel and sulfur with insignificant proportions of iron .

At the University of Giessen , Laspeyres found two more specimens with the same crystals which, according to the label, came from "from the Siegenschen" and from "Grünau in the county of Sayn-Altenkirchen ". For Laspeyres there was no question that the first stage also came from one of these sites. Laspeyres named the newly discovered mineral in its first description in 1876 based on its frequent occurrence in the form of crystal twins after the ancient Greek words πολύ polý for 'a lot' and δυμος didymos for 'twin'.

Based on research from Laspeyre, the green ore mine, which has been closed since 1912 (see also Eisernhardt mine ) with siderite veins as well as copper, cobalt and nickel ores (also known as Grüne Aue or Grüneau ) near Schutzbach in the Altenkirchen district (Westerwald) in Rhineland- Palatinate as a type locality .

A storage location for the type material of the mineral is not known.

classification

The current classification of the IMA counts the polydymite to the " spinel supergroup ", where together with cadmoindite , cuprorhodsite , daubréelite , greigite , indite , joegoldsteinite , kalininite , linneit , siegenite , violarite and xingzhongite the "linneit subgroup" within the "thiospinelle" "Forms (as of 2019).

Already in the outdated 8th edition of the mineral classification according to Strunz , the polydymite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with [the molar ratio ] M: S <1: 1", where together with Bornhardtite , Carrollite , Daubréelith, Greigit, Indit, Linneit, Siegenit, Trüstedtit , Tyrrellit and Violarit the "Linneit series" with the system no. II / C.01 formed.

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 old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. II / D.01-30 . In the "Lapis Classification" This also corresponds to the department "sulfides with metal: S, Se, Te <1: 1" where Polydymit with Bornhardtit, Cadmoindit, Carrollit, Cuprokalininit , daubréelite, Fletcherit , Florensovit , greigite, Indit, Kalininit, Linneit, Siegenit, Trüstedtit, Tyrrellite and Violarit form the "Linneit group" with the system no. II / D.01 forms.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and was last updated in 2009 by the International Mineralogical Association (IMA) , assigns the polydymite to the class of “sulfides and sulfosalts” and there to the department of “metal sulfides with M: S = 3: 4 and 2: 3 “. However, this is further subdivided according to the exact molar ratio, so that the mineral can be found in the sub-section "M: S = 3: 4" according to its composition, where it can be found together with bornhardtite, cadmoindite, carrollite, cuproiridsite , cuprorhodsite, daubréelite , ferrorhodsite , Fletcherit, Florensovit, Greigit, Indit, Kalininit, Linneit, Malanit , Siegenit, Trüstedtit, Tyrrellite, Violarit and Xingzhongit the "Linneit Group" with the system no. 2.DA.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also assigns the polydymite to the class of "sulfides and sulfosalts" and there in the department of "sulfide minerals". Here, too, he is in the "Linneit group (isometric: Fd 3 m )" 02.10.01 within the subsection " Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 3 : 4 “to be found. Template: room group / 227

Chemism

In its pure form, polydymite (Ni 2+ Ni 3+ 2 S 4 ) consists of 57.85% nickel (Ni) and 42.15% sulfur (S).

Hugo Laspeyres found in his first analyzes to determine the chemical composition, however, that the mineral is often due to its matrix of siderite (Fe [CO 3 ]) and quartz (SiO 2 ) as well as foreign admixtures of various sulfides such as bismuthinite ( Bismutglanz , Bi 2 S 3 ), boulangerite (Pb 5 Sb 4 S 11 ), gersdorffite ( arsenic- nickel gravel , NiAsS), millerite (NiS) and ullmannite ( antimony-nickel gravel, NiSbS) is contaminated; possibly also through galena ( lead luster , PbS) and chalcopyrite ( copper pyrites , CuFeS 2 ). Morenosite ( nickel vitriol , Ni (SO 4 ) · 7H 2 O) and sulfur can also be added as decomposition products of polydymite .

Crystal structure

Polydymite crystallizes cubically in the space group Fd 3 m (space group no. 227) with the lattice parameter a  = 9.47  Å and 8 formula units per unit cell . Template: room group / 227

properties

Polydymite has the property of decrepitating strongly when heated, that is, of breaking with a crackling noise. Soldering tube experiments can therefore only be carried out in a closed flask. When heated, yellow sublimate of sulfur and yellowish brown sublimate of arsenic sulfide are formed. The residue remaining in the flask can easily be melted on charcoal to form a black-green magnetic ball.

Polydymite is insoluble in hydrochloric acid . In nitric acid , on the other hand, it dissolves with the separation of sulfur to a clear green solution after cooling and dilution with water.

Education and Locations

Polydymite is mainly formed in hydrothermally formed ducts . Bismuthinite , chalcopyrite , galena , millerite , pyrrhotite , pyrite , gersdorffite , ullmannite , sphalerite , quartz , siderite, among others , occur as accompanying minerals , depending on the location .

As a rather rare mineral formation, polydymite can sometimes be abundant in various places, but overall it is not very common. Around 140 sites are known to date (as of 2019). In addition to its type locality, the Grube Au near Schutzbach, the mineral was also found in Rhineland-Palatinate in the nearby Pius mine and in the Wingertshardt mines near Katzwinkel , Käusersteimel , Fischbacher Werk and Lammerichskaule in the Altenkirchen district .

Other well-known sites in Germany include the Clara mine near Oberwolfach (Freiburg district) in Baden-Württemberg and the Klappertshardt mine near Hummerzheim near Bad Münstereifel, the Aurora and Dörnberg mines of the Ramsbeck trade union , the Neue Hope mine near Wilnsdorf, the Wilder mine Mann (also Wildermann ) near Müsen, the Eiserner Union mine and the Brüderbund mine in the Arnsberg district in North Rhine-Westphalia.

In Austria Polydymit has so far only in a serpentinite - Quarry at Dietmannsdorf at the Wild and in the corundum - and serpentinhaltigen Plagioklasfelsen in Wolfsbach (municipality drosendorf-zissersdorf) in Lower Austria, and at Brennkogel in the Hohe Tauern and in several places in Schwarzleograben in the community Leogang in the Salzburg region.

Other locations include Australia, China, Finland, Greece, Italy, Japan, Canada, Namibia, Romania, Russia, Zimbabwe, Slovakia, Spain, South Africa, the Czech Republic and the United States of America.

See also

literature

  • H. Laspeyres : Chemical investigations of nickel ores; 1. Polydymite, a new nickel ore . In: Journal for Practical Chemistry . tape 122 , 1876, p. 397–413 ( rruff.info [PDF; accessed June 13, 2019]).

Web links

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

Individual evidence

  1. ↑ a b c d e 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.  93 (English).
  2. ↑ a b Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2019. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2019, accessed May 20, 2019 .
  3. ↑ a b c d e f Polydymite . 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]).
  4. ^ David Barthelmy: Polydymite Mineral Data. In: webmineral.com. Retrieved June 13, 2019 .
  5. ↑ a b 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 .
  6. ↑ 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. 100-101 .
  7. ↑ a b c d H. Laspeyres : Chemical investigations of nickel ores; 1. Polydymite, a new nickel ore . In: Journal for Practical Chemistry . tape  122 , 1876, p. 397–413 ( rruff.info [PDF; accessed June 13, 2019]).
  8. ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  230 .
  9. ↑ Catalog of Type Mineral Specimens - P. (PDF 112 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed June 24, 2019 .
  10. ↑ Ferdinando Bosi, Cristian Biagioni, Marco Pasero: Nomenclature and classification of the spinel supergroup . In: European Journal of Mineralogy . tape 31 , no. 1 , September 12, 2018, p. 183–192 , doi : 10.1127 / ejm / 2019 / 0031-2788 (English).
  11. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 25, 2019 .
  12. ↑ Localities for Polydymite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 13, 2019 .
  13. ↑ List of locations for polydymite in the Mineralienatlas and Mindat