Bunsenite

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Bunsenite
Bunsenite - Kochhütte, Helbra, Mansfeld-Südharz, Saxony-Anhalt, Germany.jpg
Green blocky bunsenite crystals and unknown colorless crystals from Kochhütte , Helbra, Mansfeld-Südharz (image width 1 mm)
General and classification
chemical formula NOK
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.AB.25 ( 8th edition : IV / A.04)
02/04/01/02
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fm 3 m (No. 225)Template: room group / 225
Lattice parameters a  = 4.18  Å
Formula units Z  = 4
Twinning observed
Physical Properties
Mohs hardness 5.5
Density (g / cm 3 ) measured: 6.898; calculated: 6.806
Cleavage is missing
colour dark to pistachio green
Line color Brown black
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 2.37
Refractive index n  = 2.37
Birefringence none, as it is optically isotropic

Bunsenite , also outdated as nickel oxide and known under the chemical name nickel (II) oxide , is a very rarely occurring mineral from the mineral class of "oxides and hydroxides" with the chemical composition NiO.

Bunsenite crystallizes in the cubic crystal system and usually develops very small, octahedral crystals of a dark pistachio green color. Its line color , on the other hand, is brown-black. The surfaces of the transparent to translucent crystals show a glass-like sheen .

Etymology and history

Robert Bunsen
between 1852 and 1877

The mineral was first described in 1858 by Carl Wilhelm Bergemann , who initially referred to it as nickel oxide . He discovered it in a sample from the area around Johanngeorgenstadt in the Ore Mountains , which he had received from the mineralogist and mineral dealer Adam August Krantz . He in turn found the sample in a collection bought in 1857 in Schneeberg.

Altogether, Bergemann was able to identify three new minerals at the stage, namely in addition to nickel oxide , aerugite and xanthiosite . The former was already known by Henri Victor Regnault and Robert Wilhelm Bunsen as "artificial crystalline nickel oxide".

The name Bunsenite, which is still valid today, was given to the mineral in 1868 by James Dwight Dana , who named the mineral after Robert Wilhelm Bunsen .

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , bunsenite belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with the molar ratio of metal: oxygen = 1: 1 and 2: 1 (M 2 O, MO) ", where together with calcium oxide , manganosite , monteponite , murdochite , periclase and wüstite the" periclase group "with the system no. IV / A.04 .

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 bunsenite to the category of "oxides and hydroxides with the molar ratio of metal: oxygen = 2: 1 and 1: 1" . However, this is further subdivided according to the exact molar ratio and the relative size of the cations involved, so that the mineral is classified according to its composition in the subsection “Cation: Anion (M: O) = 1: 1 (and up to 1: 1.25); with only small to medium-sized cations "can be found, where together with calcium oxide, ferropericlase, manganosite, monteponite, periclase, wüstite the" periclase group "with the system no. 4.AB.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns bunsenite to the class of "oxides and hydroxides" and there into the category of "oxides". Here, too, he is in the " Periclas Group (Isometric, Fm-3m) " with the system no. 04.02.01 to be found within the subsection “Simple oxides with a cation charge of 2+ (AO)”.

Crystal structure

Crystal structure of bunsenite

Bunsenite crystallizes in the cubic crystal system with the space group Fm 3 m (space group no. 225) with the lattice parameter a  = 4.18  Å and four formula units per unit cell . The crystal structure corresponds to that of sodium chloride . Template: room group / 225

Education and Locations

Bunsenite forms in nickel ores under hydrothermal conditions at around 730 ° C and less than 2000 bar through metamorphosis . Depending on where it was found, the mineral can be found with various accompanying minerals . So it occurs at its type locality near Johanngeorgenstadt in Saxony in association with bismuth , annabergite , aerugite and xanthiosite .

As a very rare mineral formation, Bunsenite is so far (as of 2018) only known in a few samples from less than 10 sites, whereby in Germany, apart from Johanngeorgenstadt, it is still in the vicinity of the nearby town of Marienberg and about 1.5 km northwest of it on the Abrahamhalde am Schacht 139 (not to be confused with the father Abraham Schacht , Wismutschacht 152) near Lauta in Saxony and in the Kochhütte (also August-Bebel-Hütte) near Helbra in Saxony-Anhalt.

In a nickel deposit and the Scotia talc mine near Bon Accord in the South African province of Mpumalanga , Bunsenite appeared in the company of Liebenbergite , Trevorite , Violarite , Millerite , Gaspéit , Nimit and Bonaccordite, which was first discovered there and named after its type locality . Bunsenite could also be found in the Morokweng crater , which was formed by the impact of an asteroid and was discovered in the Kalahari desert in 1994 .

Other previously known sites are the Kambalda deposit in Coolgardie Shire in the Australian state of Western Australia, the old Sarggejok (Sargejok) gold mining site near Karasjok in the Norwegian province (Fylke) Finnmark and a gold deposit on the Aidyrlya River in the Russian Orenburg Oblast .

See also

literature

Web links

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

Individual evidence

  1. ^ A b 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.  185 .
  2. ↑ a b c d e Bunsenite . 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; 61  kB ; accessed on April 1, 2018]).
  3. ↑ C. Bergemann: XXVI. About some nickel ores . In: Journal for Practical Chemistry . tape 75 , 1858, pp. 239–244 ( rruff.info [PDF; 221 kB ; accessed on April 1, 2018]).
  4. ↑ Thomas Witzke : The discovery of Bunsenit at www.strahl.org
  5. ^ JD Dana, GJ Brush: A System of Mineralogy . 5th edition. John Wiley and Sons, New York 1868, p. 134–135 ( rruff.info [PDF; 153 kB ; accessed on April 1, 2018]).
  6. ↑ a b c List of localities for bunsenite in the Mineralienatlas and in Mindat