Cerite

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Cerite
Cerite- (Ce) 2-Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada.jpg
Cerit- (Ce) from Mont Saint-Hilaire, Québec, Canada
General and classification
other names
  • Cerite (Ce)
  • Cerit- (La)
chemical formula see single minerals
Mineral class
(and possibly department) 		Silicates and Germanates
System no. to Strunz
and to Dana 		9.AG.20 ( 8th edition : VIII / B.19)
April 52, 2006 or April 52, 2006-02
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol ditrigonal-pyramidal; 3 m
Room group (no.) R 3 c (No. 161)
Lattice parameters see crystal structure
Formula units Z  = 6
Physical Properties
Mohs hardness 5 to 5.5
Density (g / cm 3 ) 4.75 to 4.86
Cleavage is missing
Break ; Tenacity uneven
colour reddish brown or brown
Line color gray-white or white
transparency translucent to opaque
shine Glass gloss to diamond gloss
radioactivity weakly radioactive
Crystal optics
Optical character uniaxial positive

Cerite is a collective name for the two rarely occurring, cerium- containing minerals cerite (Ce) and cerite (La) from the mineral class of " silicates and germanates ". Both crystallize in the trigonal crystal system with the chemical composition

  • Cerite- (Ce) - (Ce, La, Ca) 9 (Fe 3+ , Mg) [(OH) 3 | SiO 3 (OH) | (SiO 4 ) 6 ]
  • Cerite- (La) - (La, Ce, Ca) 9 (Fe 3+ , Mg) [(OH) 3 | SiO 3 (OH) | (SiO 4 ) 6 ]

and usually only develop small crystals in the millimeter range from reddish-brown or light yellow to pink-brown color and gray-white to white line color .

There are numerous variants of cerite in which the element cerium is replaced by lanthanum or yttrium .

Etymology and history

Both minerals were named after cerium because of their content.

The later Cerit- (Ce) was first discovered in 1750 near Bastnäs in the Swedish municipality of Skinnskatteberg . Axel Frederic Cronstedt called the mineral "tungstone" because of its high density, but Carl Wilhelm Scheele did not find the element tungsten that he discovered in the ore from Bastnäs, which occurs in other tungstones . He therefore called the mineral a "false tungstone". Wilhelm von Hisinger and Jöns Jakob Berzelius examined the fake Tungstein more closely and finally recognized that it must contain a previously unknown element, which they named after the dwarf planet Ceres Cerium . The mineral was named accordingly by them.

Cerit- (La), on the other hand, could only be detected in 2001 in the “Material'naya tunnel” in the Hackmantal on the Yuksporr in the Russian Chibinen massif . The mineral was analyzed and described by Yakov A. Pakhomovsky, Yury P. Men'shikov, Victor N. Yakovenchuk, Gregory Yu. Ivanyuk, Sergey V. Krivovichev, and Peter C. Burns.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , cerite (Ce) and cerite (La) belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates with non-tetrahedral anions (Neso subsilicates) “, Where they formed an independent group together with Kuliokit- (Y) , Törnebohmit- (Ce) and Törnebohmit- (La) .

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 Cerit- (Ce) and Cerit- (La) to the class of "Silicates and Germanates" and there in the department of " Island Silicates (Nesosilicates)". This section is, however, further subdivided according to the existing further anions and the coordination of the cations involved, so that the two minerals can be found according to their composition in the subsection of "Island silicates with additional anions and cations in mostly [6] and> [6] coordination" are where they form the unnamed group 9.AG.20 together with aluminocerite- (Ce) .

The systematics of minerals according to Dana also assigns cerite (Ce) and cerite (La) to the class of "silicates and germanates", but there in the more precisely defined division of "island silicates: SiO 4 groups and O, OH" , F and H 2 O ”. Here the two minerals are named after the "Cerit group" with the system no. April 52, 2006 and the other member Aluminocerit- (Ce) within the subsection " Island silicates: SiO4 groups and O, OH, F and H 2 O with cations in [6] and / or> [6] coordination ".

Crystal structure

Cerite- (Ce) crystallizes trigonal in the space group R 3 c (space group no. 161) with the lattice parameters a  = 10.78  Å and c  = 38.06 Å and 6 formula units per unit cell .

Cerit- (La) also crystallizes trigonal in the space group R 3 c , but with the lattice parameters a  = 10.75  Å and c  = 38.32 Å and 6 formula units per unit cell .

properties

As with all rare earth minerals, cerite also contains traces of uranium and thorium . For this reason, the minerals of the cerite group are classified as weakly radioactive and have a specific activity of around 1403 Bq / g (Cerit- (Ce)) or 1231  Bq / g (Cerit- (La)) (for comparison: natural potassium 31.2 Bq / g).

Education and Locations

Cerite aggregate with actinolite and brochantite from the Bastnäs mine, Sweden

Cerite form in hydrothermally in quartz - barite - carbonatite veinlets with high content of rare-earth metals . Accompanying minerals include aegirine , allanite , anatase , ankylite- (Ce) , barylite , barite, bastnäsite , catapleiite , chabazite-ca , edingtonite , epidote , fluorite , galena , monazite , quartz, törnebohmit and uraninite .

Cerit- (Ce) has been detected at around 40 sites worldwide so far (as of 2010), including in South Australia ; at Bobritzsch-Hilbersdorf in Germany; Piedmont in Italy; near Bujumbura in Burundi; Ontario and Québec in Canada; in the Mongolian Altai Mountains ; Khomas in Namibia; Nordland and Telemark in Norway; Eastern Siberia , Kola and Urals in Russia; Gauteng in South Africa; in addition to its type locality Bastnäs Mine in some other regions of Västmanland and Dalarna in Sweden and in several regions of California , Colorado , Connecticut and New York in the USA.

Cerit- (La) could only be detected at its type locality Hackmantal in Russia.

See also

literature

  • John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Cerite- (Ce) , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 73.3 kB )

Web links

Commons : Cerite  - collection of pictures, videos and audio files
  • Mineral Atlas: Cerit- (Ce) and Cerit- (La) (Wiki)
  • The Canadian Mineralogist : CERITE- (La), (La, Ce, Ca) 9 (Fe, Ca, Mg) (SiO4) 3 [SiO3 (OH)] 4 (OH) 3, A NEW MINERAL SPECIES FROM THE KHIBINA ALKALINE MASSIF : OCCURRENCE AND CRYSTAL STRUCTURE by Yakov A. Pakhomovsky, Yury P. Men'shikov, Victor N. Yakovenchuk, Gregory Yu. Ivanyuk, Sergey V. Krivovichev, and Peter C. Burns

Individual evidence

  1. ^ A b 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. 554 .
  2. ↑ American Mineralogist Crystal Structure Database - Cerite- (La) (English, 2002)
  3. ↑ a b c Webmineral - Cerite- (La)
  4. ↑ Willhelm Hisinger, Jöns Jacob Berzelius: Cerium, a new metal from a Swedish type of stone, called Bastnaes Tungstein / described by W [illhelm] Hisinger and J [öns Jacob] Berzelius. In: New General Journal of Chemistry. 1804, 2, pp. 397-418 ( abstract ).
  5. ^ 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. 554 .
  6. ↑ American Mineralogist Crystal Structure Database - Cerite- (La) (English, 2002)
  7. ↑ - Webmineral - Cerite- (Ce) (English)
  8. ↑ Mindat - Localities for Cerite- (Ce)
  9. ↑ Mindat - Cerite- (La) (English)