Olympite

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Olympite
General and classification
other names

IMA 1979-065

chemical formula Na 5 Li [4] [PO 4 ] 2
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.AA.30 ( 8th edition : VII / A.01)
04/38/10/02
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidal; 222
Room group (no.) P 2 1 2 1 2 1 (No. 19)
Lattice parameters a  = 10.12  Å ; b  = 14.79 Å; c  = 10.13 Å
Formula units Z  = 8
Physical Properties
Mohs hardness 4th
Density (g / cm 3 ) measured: 2.8; calculated: 2.85
Cleavage Please complete!
Break ; Tenacity clamshell; brittle
colour colorless
Line color White
transparency translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.510
n β  = 1.510
n γ  = 1.512
Birefringence δ = 0.002
Optical character biaxial positive
Axis angle 2V = 46 ° (measured)
Other properties
Chemical behavior Easily soluble in water, quickly decomposes on contact with air

Olympite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the orthorhombic crystal system with the composition Na 5 Li [4] [PO 4 ] 2 , so it is chemically a sodium - lithium phosphate.

So far, Olympite could only be found in the form of small, oval crystal grains about five millimeters in size. The surfaces of the colorless and translucent crystals have a glass-like sheen .

Special properties

Olympit dissolves easily in cold water, creating a strongly alkaline solution. Even if it comes into contact with air, it rapidly decomposes into sodium carbonate and aqueous sodium phosphate .

Etymology and history

Olympit was discovered in 1979 on Razvumchorr (Russian: Расвумчорр), which belongs to the Chibinen mountain range on the Russian Kola peninsula . It was first described in 1980 by Aleksandr Petrovich Khomyakov, AV Bykova and Yu. A. Malinovskii, who named the mineral after the Olympic Games that were held in Moscow that year .

Type material of the mineral was found in the Geological Museum (Kola branch) of the Academy of Sciences (Register No. 5533), in the Mining Institute of St. Petersburg (Register No. 1208/1), in the Museum of the Institute of Mineralogy and Geochemistry of Rare Elements (IMGRE) and in the AE Fersman Mineralogical Museum of the Academy of Sciences (register no. 80180).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the olympite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates without foreign anions ", where it belongs together with alarsite , berlinite , beryllonite , Hurlbutit , Lithiophosphat , Nalipoit and Rodolicoit the unnamed group VII / A.01 formed.

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 the Olympite to the class of “phosphates, arsenates and vanadates” and there to the category of “phosphates, etc. without additional anions; without H 2 O “. However, this section is further subdivided according to the relative size of the cations involved , so that the mineral, according to its composition, can be found in the sub-section “With small cations (some also with larger cations)”, where it is the only member of the unnamed group 8. AA.30 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Olympite to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc." Here it is together with lithiophosphate and nalipoite in the "lithiophosphate group" with the system no. 38.04.10 can be found in the subsection “ Anhydrous phosphates etc., A + XO 4 ”.

Education and Locations

Olympite forms as an ultra-alkaline phase in nepheline - syenite - pegmatites .

So far (as of 2012) Olympite could only be detected at two sites in Russia: At its type locality Raswumtschorr in the Chibinen, the mineral occurred in paragenesis with Sidorenkite , Dorfmanite , Nahpoit , Villiaumite , Shafranovskit and Aegirin . In the Lowosero-Tundra massif, which is also located on the peninsula , Olympite appeared together with natrite and natrosilite .

Crystal structure

Olympite crystallizes orthorhombically in the space group P 2 1 2 1 2 1 (space group no. 19) with the lattice parameters a  = 10.12  Å ; b  = 14.79 Å and c  = 10.13 Å and 8 formula units per unit cell .

See also

literature

  • Michael Fleischer, Adolf Pabst: New Mineral Names , in: American Mineralogist , Volume 66, pp. 436–439, 1981 ( PDF 442.9 kB; p. 3 )

Web links

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  426 .
  2. ↑ Webmineral - Olympite
  3. ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Olympite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ([PDF kB])
  4. ↑ a b c d Mindat - Olympite
  5. ↑ Michael Fleischer, Adolf Pabst: New Mineral Names , in: American Mineralogist , Volume 66, pp. 436–439, 198l ( PDF 442.9 kB; p. 3 )