Fedorite

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Fedorite
Charoite, Aegirine, Fedorite (4) - Vostochnyi Mine, Murun-Massif, Russia.JPG
Orange-yellow fedorite crystals in fibrous, leafy charoite with black
aegirine suns from the Vostochnyi mine, Murun massif ( Aldan highlands ), Yakutia, Russia (size: 4.3 cm × 3.3 cm)
General and classification
chemical formula
  • (K, Na) 2.5 (Ca, Na) 7 Si 16 O 38 (OH, F) 2 • 3.5H 2 O
  • (K, Na) 2.4 (Ca, Na) 7 [(OH, F) 2 | (Si 8 O 19 ) 2 ] · H 2 O
Mineral class
(and possibly department) 		Silicates and germanates - layered silicates (phyllosilicates)
System no. to Strunz
and to Dana 		9.EE.80 ( 8th edition : VIII / H.34)
73.01.03.01
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Space group C 1 (No. 2, position 3)Template: room group / 2.3
Lattice parameters a  = 9.6300 (7)  Å ; b  = 9.6392 (7) Å; c  = 12.6118 (9) Å
α  = 102.422 (1) °; β  = 96.227 (1) °; γ  = 119.888 (1) °
Formula units Z  = 1
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) measured: 2.43 to 2.58; calculated: [2.43]
Cleavage completely mica-like after {001}
colour colorless, cream to pearly white, pale red
Line color White
transparency transparent to translucent
shine Glass gloss, silk gloss, pearl gloss
Crystal optics
Refractive indices n α  = 1.522
n β  = 1.530
n γ  = 1.531
Birefringence δ = 0.009
Optical character biaxial negative
Axis angle 2V = 32 ° (measured); 38 ° (calculated)
Other properties
Chemical behavior insoluble in acids, easily meltable

Fedorite is a very rarely occurring mineral from the mineral class of " silicates and germanates " with the chemical composition (K, Na) 2.5 (Ca, Na) 7 Si 16 O 38 (OH, F) 2 · 3.5H 2 O The elements potassium , sodium and calcium as well as fluorine and hydroxide ions indicated in round brackets can represent each other in the formula ( substitution , diadochy), but are always in the same proportion to the other components of the mineral.

Fedorite crystallizes in the triclinic crystal system and develops pseudo-hexagonal, mica-like tabular crystals , which are similar to those of muscovite .

In its pure form, fedorite is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also be translucent cream to pearly white and take on a pale red color due to foreign admixtures.

Etymology and history

Evgraf Stepanowitsch Fyodorow (1853-1919)

Fedorite was first discovered in the Turiy massif ( Mys Tury ) on the Kola Peninsula in the Murmansk Oblast of northwestern Russia . The scientific description of the mineral was made in 1965 by Aleksandr Aleksandrovich Kukharenko , MP Orlova, and AG Bulakh, who named it after the Russian mathematician, crystallographer and mineralogist Evgraf Stepanowitsch Fyodorov . Fyodorov ( Fedorev ) was very interested in mathematical group theory and presented important concepts for polytypism and the theory of the plane, crystallographic group (English: "wallpaper theory" or "wallpaper group"), which were later used in the solution of crystal structures .

Type material of the mineral is in the Mineralogical Museum of the University of Saint Petersburg under the catalog no. 1505 / 2-3, in the Geological Museum of the Science Center of the Russian Academy of Sciences in Apatity on Kola under catalog no. 1873 and in the Fersman Museum in Moscow under catalog no. 73038-73040, 73371, 73772 and vis5121.

classification

Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of fedorite belonged to the mineral class of "silicates and Germanates" and then to the Department of "phyllosilicates (phyllosilicates)" where he collaborated with Armstrongit , Gyrolith , Lalondeit , Martinit , Minehillit , Orlymanit , Reyerit , truscottite , Tungusit and Zeophyllit the "Reyeritgruppe" with the system no. VIII / H.34 .

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 fedorite to the “layered silicates” department. This is, however, further subdivided according to the structure of the layers, so that the mineral, according to its structure, can be found in the sub-section “Simple tetrahedral networks of 6-membered rings, connected by octahedral networks or bands”, where it can only be found together with martinite forms unnamed group 9.EE.80 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns fedorite to the class of "silicates and Germanates", but there in the more finely subdivided division of "layered silicates with condensed tetrahedral layers". Here he is the only member of the unnamed group 73.01.03 within the subdivision layered silicates: to find condensed tetrahedral layers with double layers .

Crystal structure

Fedorite crystallizes triclinic in the space group P 1 (space group no. 2) . The lattice parameters measured on samples from different locations resulted in the following values for one formula unit per unit cell : Template: room group / 2

  • a  = 9.6300 (7)  Å ; b  = 9.6392 (7) Å; c  = 12.6118 (9) Å; α = 102.422 (1) °; β = 96.227 (1) ° and γ = 119.888 (1) ° for samples from the type locality Turiy massif
  • a  = 9.6450 (7)  Å ; b  = 9.6498 (7) Å; c  = 12.6165 (9) Å; α = 102.427 (1) °; β = 96.247 (1) ° and γ = 119.894 (1) ° for samples from the small Murun

Education and Locations

At its type locality in the Turiy massif on Kola, fedorite was found in fine veins in fenitized sandstone . Apophyllite , narsarsukite and quartz appeared as accompanying minerals . Other previously known sites in Russia are the Kedrowji- (Kedrovyi) massif, Podznezhnik and the (Wostochni-) Vostochnyi area as part of the Murun massif in the Aldan highlands in the Sakha Republic (Yakutia) and a large crevice eruption on the Tolbachik volcano in the distance East of Russia.

So far, only one other site is known worldwide (as of 2017), namely the Schellkopf near Brenk in the Rhineland-Palatinate district of Ahrweiler in Germany.

See also

literature

  • Aleksandr Aleksandrovich Kukharenko, MP Orlova, AG Bulakh, EA Badgasarov, OM Rimskaya-Korsakova, EI Nephedov, GA Ilinskii, AS Ergeev, NB Abakumova: The Caledonian Complex of Ultrabasic, Alkaline Rocks and Carbonatites of the Kola Peninsula and Northern Karelia . In: The Canadian Mineralogist . 1970, p. 479–481 (Russian: Каледонский комплекс ультраосновных щелочных пород и карбонатитов Кольского комплекс вир полуостров65 .
  • Michael Fleischer : New Mineral Names . In: The American Mineralogist . tape 52 , 1967, p. 559-564 ( minsocam.org [PDF; 444 kB ; accessed on November 20, 2017]).
  • Roger H. Mitchell, Peter C. Burns: The structure of Fedorite: A re-appraisal . tape 39 , no. 3 , June 2001, p. 769-777 , doi : 10.2113 / gscanmin.39.3.769 ( psu.edu [PDF; 242 kB ; accessed on November 20, 2017]).
  • Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 587 .
  • Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 752 (first edition: 1891).

Web links

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

Individual evidence

  1. ↑ a b IMA / CNMNC List of Mineral Names; September 2017 (PDF 1.67 MB)
  2. ^ 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.  683 .
  3. ↑ The numbering of this axis position does not correspond to the order of the International Tables for Crystallography , because it is not listed there.
  4. ^ A b Roger H. Mitchell, Peter C. Burns: The structure of Fedorite: A re-appraisal . tape 39 , no. 3 , June 2001, p. 769-777 , doi : 10.2113 / gscanmin.39.3.769 .
  5. ↑ a b c Fedorite . 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; 76  kB ; accessed on November 19, 2017]).
  6. ^ A b 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. 1547 .
  7. ↑ 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 .
  8. ↑ a b c d e Mindat - Fedorite (English)
  9. ↑ Mineral Atlas: Fedorit
  10. ↑ Find location list for fedorite in the Mineralienatlas and Mindat