Bøggildit

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Bøggildit
General and classification
other names

Böggildit

chemical formula Sr 2 Na 2 [Al 2 F 9 | PO 4 ]
Mineral class
(and possibly department)
Halides
System no. to Strunz
and to Dana
3.CG.20 ( 8th edition : III / C.05)
01/12/06/01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / c (No. 14)Template: room group / 14
Lattice parameters a  = 5.25  Å ; b  = 10.46 Å; c  = 18.58 Å
β  = 107.5 °
Formula units Z  = 4
Twinning polysynthetic according to {001}
Physical Properties
Mohs hardness 4 to 5
Density (g / cm 3 ) measured: 3.66; calculated: 3.692
Cleavage is missing
Break ; Tenacity just
colour light red to meat red
Line color White
transparency translucent
shine Glass luster; Greasy sheen on fractured surfaces
Crystal optics
Refractive indices n α  = 1.462
n β  = 1.466
n γ  = 1.469
Optical character biaxial positive
Axis angle 2V = measured: 78 to 80 °; calculated: 80 °

Bøggildit (also Böggildit ) is a very rarely occurring mineral from the mineral class of " halides " with the chemical composition Sr 2 Na 2 [Al 2 F 9 | PO 4 ] and thus belongs to complexly composed strontium - sodium - aluminofluorides with an additional phosphate group .

Bøggildit crystallizes in the monoclinic crystal system and is mostly found in columnar mineral aggregates with prismatic and longitudinally striped crystals of up to 12 millimeters in length. On uninjured areas of the light-red to flesh-red crystals, a glass-like sheen appears , whereas fractured surfaces have a more greasy sheen.

Etymology and history

Was first discovered Bøggildit in cryolite - deposit at Ivittuut in southwest Greenland . It was scientifically described in 1951 by the Danish geologist Richard Bøgvad (1897–1952), who named the mineral after his old teacher, Professor Ove Balthasar Bøggild (1872–1956).

The type material of the mineral is at the University of Copenhagen in Denmark under the catalog no. 1857.155a kept.

classification

In the outdated 8th edition of the mineral classification according to Strunz , the Bøggildite belonged to the mineral class of "halides" and there to the division of "double halides, water-containing", where it formed the unnamed group III / C.05 together with stenonite .

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 Bøggildite to the “halides” class, but in the “complex halides” department. This division is also further divided by the crystal structure, so that the mineral according to its structure in the subsection "Aluminofluoride with CO 3 , SO 4 , PO 4 " is to be found where it is the only member of the unnamed group 3.CG.20 forms .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Bøggildit to the class of "halides" and there in the department of "halide compounds". Here he is to be found as the only member of the unnamed group 01/12/06 within the subsection “ Halide compounds with various anions ”.

Crystal structure

Bøggildit crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a  = 5.25  Å ; b  = 10.46 Å; c  = 18.58 Å; β = 107.5 ° and 4 formula units per unit cell . Template: room group / 14

Education and Locations

Bøggildit forms within greisen in the contact zone of cryolite ore bodies . In addition to cryolite, the accompanying minerals include albite , chalcopyrite , fluorite , galena , molybdenite , muscovite , pyrite , quartz , sphalerite and zirconium .

Apart from the type locality Ivittuut in Greenland, no other location for Bøggildit is known so far (as of 2012).

See also

literature

  • Richard Bøgvad: Mineralogical observations on the cryolite deposite at Ivigtut, Greenland . In: Meddelelser fra Dansk Geologisk Forening . tape 12 , 1951, pp. 109–110 (English, available online at 2dgf.dk [PDF; 520 kB ; accessed on March 31, 2019]).
  • Michael Fleischer : New Mineral Names . In: American Mineralogist . tape 39 , 1954, pp. 848–852 (English, available online at rruff.info [PDF; 313 kB ; accessed on March 31, 2019]).
  • Michael Fleischer: New Mineral Names. New data . In: American Mineralogist . tape 41 , 1956, pp. 958–960 (English, available online at rruff.info [PDF; 178 kB ; accessed on March 31, 2019]).

Web links

Individual evidence

  1. a b c 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 .
  2. 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.  167 (English).
  3. David Barthelmy: Boggildite MineralData. In: webmineral.com. (English).
  4. a b c d e Bøggildite . 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; 66  kB ; accessed on March 31, 2019]).
  5. a b c d e Bøggildite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 31, 2019 .
  6. ^ Arne Noe-Nygaard: Richard Bøgvad (November 1, 1897 - August 7, 1952) . In: Meddelelser fra Dansk Geologisk Forening . tape 12 , no. 2 , 1952, pp. 315–318 (Danish, available online at 2dgf.dk [PDF; 1.1 MB ; accessed on March 31, 2019]).