Magnesiocoulsonite

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Magnesiocoulsonite
General and classification
other names
  • IMA 1994-034
  • Vanadium spinel
chemical formula
  • MgV 2 O 4
  • Mg (V 3+ , Cr 3+ ) 2 O 4
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.BB.05 ( 8th edition : IV / B.03)
02/07/04/03
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  = 8.38  Å
Formula units Z  = 8
Physical Properties
Mohs hardness 6.5 ( VHN 100 = 873-1080, average 969)
Density (g / cm 3 ) measured: not defined; calculated: 4.31
Cleavage is missing
Break ; Tenacity uneven; brittle
colour black; light gray in incident light
Line color black
transparency opaque
shine Metallic luster
Other properties
Chemical behavior insoluble in nitric acid (HNO 3 )

Magnesiocoulsonite is a very rarely occurring mineral from the mineral class of "oxides and hydroxides" and crystallizes in the cubic crystal system with the idealized chemical composition MgV 2 O 4 . Chemically, Magnesiocoulsonit therefore a magnesium - vanadium - oxide or Vanadinspinell because it structurally to the group of spinels belongs.

Magnesiocoulsonite is the magnesium analogue of coulsonite (FeV 2 O 4 ) similar to the analogue pair chromite (FeCr 2 O 4 ) -  magnesiochromite (MgCr 2 O 4 ) and forms a mixed crystal row with the latter . Due to the mixed crystal formation, part of the vanadium is usually replaced ( substituted ) by chromium , which is why the formula is also given in various sources as Mg (V 3+ , Cr 3+ ) 2 O 4 .

So far, magnesiocoulsonite could only be discovered in the form of irregular or coarse octahedral grains up to about 0.3 mm in diameter. The mineral is opaque and shows a metallic sheen on the surfaces of the black crystallites . The line color of magnesiocoulsonite is also black, whereas the reflection color under the incident light microscope looks light gray.

Etymology and history

The synthetic compound MgV 2 O 4 was already presented in 1947 by Walter Rüdorff and Bertold Reuter and its crystal structure was examined.

The natural formation of the compound was first in marble - quarry Pereval (also pit Kaber ) in Slyudyanka near Lake Baikal in the Russian region of Siberia discovered and 1995 LS Resnizki, Je. W. Skljarov and SF Uschtschaporskaya described. Based on its magnesium content and its relationship with coulsonite , Skljarow and Uschtschaporskaja named the mineral magnesiocoulsonite ( Russian Магнезиокулсонит ).

The type material of the mineral is in the Fersman Museum in Moscow named after the well-known mineralogist Alexander Fersman under the catalog no. 88235-88237 kept.

classification

The current classification of the International Mineralogical Association (IMA) is one of the Magnesiocoulsonit to spinel supergroup , where he together with chromite , Cochromit , Coulsonit , Cuprospinell , Franklinite , Gahnit , Galaxit , Hercynit , Jakobsit , Magnesiochromite , Magnesioferrit , magnetite , Manganochromit , spinel , Trevorit , Vuorelainenit and Zincochromit forming the spinel subgroup within the Oxispinelle.

Already in the outdated, but still in use 8th edition of the mineral classification according to Strunz , magnesiocoulsonite belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with a metal: oxygen ratio of 3: 4 (spinel type M 3 O 4 and related Compounds) ”, where together with brunogeierite , coulsonite, qandilite , ulvöspinell , vuorelainenite the group of“ V / Ti / Ge spinels ”with the system no. IV / B.03 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, also classifies magnesiocoulsonite in the oxides division with a substance ratio of “metal: oxygen = 3: 4 and comparable”. This, however, is further divided according to the relative size of the participating cations , is so that the mineral according to its composition in the subdivision to find "With only medium-sized cations" where it along with Brunogeierit , chromite, Cochromit, Coulsonit, Cuprospinell, Filipstadit , Franklinite, Gahnite, galaxite, hercynite, jacobsite, magnesiochromite, magnesioferrite, magnetite, manganochromite, nichromite (N), qandilite , spinel, trevorite, ulvöspinell , vuorelainenit and zincochromite the "spinel group" with the system no. 4.BB.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns magnesiocoulsonite to the class of "oxides and hydroxides" and there in the section "multiple oxides". Here it is together with coulsonite and vuorelainenite in the " vanadium subgroup " with system no. 07.02.04 can be found in the subsection “Multiple oxides (A + B 2+ ) 2 X 4 , spinel group”.

Chemism

The theoretical composition of MgV 2 O 4 contains 12.78% by weight magnesium (Mg), 53.57% by weight vanadium (V) and 33.65% oxygen (O). In the oxide form, this corresponds to 21.19% by weight of MgO and 78.81% by weight of V 2 O 3 . In contrast, the examined samples from the Pereval type locality in Russia contained only 20.90% MgO and 50.07% V 2 O 3 , but an additional 28.09% C 2 O 3 , which suggests mixed crystal formation with magnesiochromite , as well as smaller ones Additions of 0.36% Al 2 O 3 , 0.2% FeO , 0.18 MnO and 0.14% TiO 2 .
Based on four oxygen atoms, the empirical formula (Mg 0.99 Fe 0.01 ) Σ = 1.00 (V 1.28 Cr 0.71 Al 0.01 ) Σ = 2.00 O 4.00 or the idealized mixed formula Mg (V 3+ , Cr 3+ ) 2 O 4 .

Crystal structure

Magnesiocoulsonite crystallizes cubically in the spinel structure with the space group Fd 3 m (space group no. 227) , the lattice parameter a  = 8.38  Å and 8 formula units per unit cell . Template: room group / 227

properties

The mineral is insoluble in hydrochloric acid (HCl) and nitric acid (HNO 3 ). Neither bi- nor internal reflections can be seen under the incident light microscope . Possible pleochroistic properties could not be observed either.

Education and Locations

Magnesiocoulsonite forms as an accessory component in metamorphic rocks containing chromium and vanadium . Tremolite , goldmanite , chlorine and muscovite as well as calcite , kämmererite , florensovite , kalininite , karelianite , vanadium-containing magnesiochromite , pyrite and quartz also occur as accompanying minerals .

The only known location for magnesiocoulsonite is its type locality Pereval in Eastern Siberia, Russia.

See also

literature

  • Walter Rüdorff, Bertold Reuter: The structure of the magnesium and zinc vanadium spinels. Contribution to the structure of spinels . In: Journal of Inorganic and General Chemistry . tape 253 , May 1947, p. 194-208 , doi : 10.1002 / zaac.19472530311 .
  • Bertold Reuter, R. Aust, G. Colsmann, C. Neuwald: About oxide systems with transition metal ions in different stages of oxidation. XIX. Representation and properties of vanadium (II) -containing and thus n-conducting vanadium (III) spinels . In: Journal of Inorganic and General Chemistry . tape 500 , 1983, pp. 188-198 , doi : 10.1002 / zaac.19835000522 .
  • LZ Reznitskiy, EV Sklyarov, ZF Ushchaporskaya: Magnesiocoulsonite MgV 2 O 4 - a new mineral species in the spinel group . In: Zapiski Vserossiyskogo Mineralogicheskogo Obshchestva . tape 124 , no. 4 , 1995, p. 91 .
  • John Leslie Jambor , Vladimir A. Kovalenker, Jacek Puziewics, Andrew C. Roberts: New mineral names . In: American Mineralogist . tape 81 , 1996, pp. 1282–1286 ( rruff.info [PDF; 482 kB ; accessed on September 3, 2018]).

Web links

Individual evidence

  1. ↑ a b c IMA / CNMNC List of Mineral Names; March 2018 (English, PDF 1.65 kB)
  2. ↑ a b c Walter Rüdorff, Bertold Reuter: The structure of the magnesium and zinc vanadium spinels. Contribution to the structure of spinels . In: Journal of Inorganic and General Chemistry . tape 253 , May 1947, p. 194-208 , doi : 10.1002 / zaac.19472530311 .
  3. ↑ 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.  189 (English).
  4. ↑ a b c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  5. ↑ a b c d e f g h i j Magnesiocoulsonite . 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]).
  6. ↑ a b Webmineral - Magnesiocoulsonite (English)
  7. ↑ a b c 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. 303-304 .
  8. ↑ Mindat - Magnesiocoulsonite (English)
  9. ↑ Cristian Biagioni, Marco Pasero: The systematics of the spinel-type minerals: An overview . In: American Mineralogist . tape 99 , no. 7 , 2014, p. 1254–1264 , doi : 10.2138 / am.2014.4816 (English, preliminary version online [PDF]).
  10. ↑ John L. Jambor , Vladimir A. Kovalenker, Jacek Puziewics, Andrew C. Roberts: New mineral names . In: American Mineralogist . tape  81 , 1996, pp. 1282–1286 ( rruff.info [PDF; 482 kB ; accessed on September 3, 2018]).
  11. ↑ Find location list for magnesiocoulsonite at the Mineralienatlas and at Mindat