Cobaltite

from Wikipedia, the free encyclopedia
Cobaltite
Cobaltite-pb21b.jpg
Cobaltite from Håkansboda, Lindesberg , Västmanland, Sweden
General and classification
other names
  • Cobalt gris
  • Cobalt éclatant
  • Cobalt gloss or glossy cobalt
  • Cobaltine or cobaltine
  • White cobalt
chemical formula CoAsS
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.EB.25 ( 8th edition : II / C.06a)
02.12.03.01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-pyramidal; mm 2
Space group Pca 2 1 (No. 29)Template: room group / 29
Lattice parameters a  = 5.59  Å ; b  = 5.58 Å; c  = 5.58 Å
Formula units Z  = 4
Frequent crystal faces {100}, {111}, {110}, rarely also {210}
Twinning after {111} and {011} pseudocubic twins
Physical Properties
Mohs hardness 5.5
Density (g / cm 3 ) 6.3
Cleavage completely after {001}
Break ; Tenacity uneven
colour silver-white, tapering reddish gray
Line color grey black
transparency opaque
shine Metallic luster
Other properties
Chemical behavior soluble in hot nitric acid

Cobaltit , as cobalt gloss , gloss cobalt , Kobaltin or cobaltite is known a commonly occurring mineral from the mineral class of " sulfides and sulfosalts " with the chemical composition CoAsS, making it chemically seen a cobalt - arsenic sulfide.

Cobaltite crystallizes in the orthorhombic crystal system and develops pseudocubic or pseudooctahedral crystals up to 8 cm in size, which are similar to those of pyrite and whose crystal faces can be striped similar to this mineral. In addition to crystals, there are also granular to coarse mineral aggregates . The mineral is in any form opaque ( opaque ) and demonstrates unweathered crystal faces a strong metallic luster . Fresh samples initially have a silver-white color with a tinge of reddish violet, but turn reddish-gray after a while in the air.

Etymology and history

In the miners' language , the mineral was already in the Middle Ages under the names cobalt gloss or gloss cobalt or Glanzkobolt known because it "bewitched by goblins" was considered. From its appearance, the ore appeared to contain profitable metals that could not be smelted. Instead, because of the arsenic content, only toxic fumes ( smelter ) were emitted when heated .

The mineral was first quantitatively analyzed and described as cobalt luster in 1797 by Martin Heinrich Klaproth . The name cobaltite (French: Cobaltine ), which is still valid today , was given to the mineral in 1832 by François Sulpice Beudant , who named it after its characteristic component, the element cobalt. Other synonyms that he recorded are cobalt gris , cobalt éclatant and white cobalt .

classification

In the 8th edition of the mineral classification according to Strunz , which was last updated in 1977 , cobaltite belonged to the mineral class of "sulfides and sulfosalts" and there to the division of "sulfides with (the molar ratio ) M (metal): S (sulfur) <1: 1" , where he named the "Cobaltin series" with the system no. II / C.06a and the other member Gersdorffit within the "Cobaltin-Ullmannit Group".

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, but continuously updated form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. II / D.18-10 . In the "Lapis Classification" This also corresponds to the department "sulfides with metal: S, Se, Te <1: 1" where Cobaltit with Gersdorffit, Hollingworthit , Irarsit , Jolliffeit , Kalungait , Milotait , Platarsit , Tolovkit , Ullmannit and Willyamite forms the "cobaltite group" (II / D.18) named after him (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 cobaltite in the category of "Metal sulfides with 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 , Gersdorffit-P2 1 3 (Rd), Gersdorffit-Pa 3 (Rd), Gersdorffit-Pca2 1 (Rd), Hollingworthit, Irarsit, Jolliffeit, Kalungait, Maslovit , Mayingit , Michenerit , Milotait, Padmait , Platarsite, 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 cobaltite to the class of "sulfides and sulfosalts" and there into the category of "sulfide minerals". Here he is also named as the " cobaltite group (cubic or pseudocubic crystals) " with the system no. 02.12.03 and the other members Gersdorffit, Ullmannit, Willyamit, Tolovkit, Platarsit, Irarsit, Hollingworthit, Jolliffeit, Padmait, Michenerit, Maslovit, Testibiopalladit, Changchengit, Milotait and Kalungait within the subdivision "Sulphides - including selenides - with the composition" A m B n X p , with (m + n): p = 1: 2 “.

Crystal structure

Cobaltite crystallizes in the orthorhombic crystal system in the space group Pca 2 1 (space group no. 29) with the lattice parameters a = 5.59  Å , b = 5.58 Å and c = 5.58 Å as well as 4 formula units per unit cell . Template: room group / 29

Crystal structure of cobaltite

  • looking parallel to the a-axis

  • looking parallel to the b-axis

  • looking parallel to the c-axis

  • spatial representation in the standard crystallographic orientation

Color table: __ Co     __ As     __ S

properties

When heated in the soldering tube , cobaltite releases the arsenic it contains as arsenic smoke. A gray, weakly magnetic ball forms. The borax pearl is colored dark blue after being roasted by the cobalt. Cobaltite is soluble in hot nitric acid .

Education and Locations

Cobaltite on calcite from the Sudbury District , Ontario, Canada

Cobaltite forms as a secondary mineral under hydrothermal conditions at high temperatures. The mineral is found as an indentation or vein in metamorphic rocks . It is often associated with cobalt-nickel sulphides and arsenides, and magnetite , sphalerite , chalcopyrite , Skutterudit , Allanit , Zoisit , scapolite , titanite and calcite (in Tunaberg, Sweden) socialized .

So far (as of 2012) cobaltite has been found at around 750 sites worldwide. Important sites are Tunaberg and Vena near Askersund in Sweden and Skutterud near Modum in Norway , cobaltite is more common in Cornwall ( England ), Ontario ( Canada ), Australia and Morocco . In Germany , cobaltite is found in the Erzgebirge , Harz and Siegerland, among others . In addition to the ones described, many smaller finds are known.

use

Cobaltite is an important raw material for the extraction of cobalt and its compounds.

See also

literature

  • RF Giese, PF Kerr : The crystal structure of ordered and disordered cobaltite . In: American Mineralogist . tape 50 , 1965, pp. 1002-1014 (English, minsocam.org [PDF; 792 kB ; accessed on July 6, 2020]).
  • Peter Bayliss: A further crystal structure refinement of cobaltite . In: American Mineralogist . tape 67 , 1982, pp. 1048–1057 (English, rruff.info [PDF; 1.1 MB ; accessed on July 6, 2020]).

Web links

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

Individual evidence

  1. ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: July 2020. (PDF; 2.44 MB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, July 2020, accessed July 6, 2020 .
  2. ^ David Barthelmy: Cobaltite Mineral Data. In: webmineral.com. Retrieved July 6, 2020 .
  3. ^ A b c 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).
  4. ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  254 .
  5. ↑ a b Cobaltite . 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; 61  kB ; accessed on July 6, 2020]).
  6. ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 253 .
  7. ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  257 .
  8. ^ FS Beudant: Traité Élémentaire de Minéralogie . 2nd Edition. Verdière, Paris 1832, p. 450–451 (French, rruff.info [PDF; 166 kB ; accessed on July 6, 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 July 6, 2020 .
  11. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  460 (first edition: 1891).
  12. ↑ Cobaltite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 6, 2020 .
  13. ↑ List of locations for cobaltite in the Mineralienatlas and Mindat , accessed on July 6, 2020.