Bastnesite

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Bastnesite
Bastnasite-155010.jpg
Bastnasite crystal from the Manitou District, El Paso County (Colorado) , USA (size: 4.3 × 3.8 × 3.3 cm)
General and classification
other names

Lanthanide fluorocarbonates

chemical formula (Ce, La, Nd, Y) [(F, OH) | CO 3 ]
Mineral class
(and possibly department) 		Carbonates and nitrates
System no. to Strunz
and to Dana 		5.BD.20a ( 8th edition : V / C.07)
16a.01.01 to 16a.01.02
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol ditrigonal-dipyramidal; 6 m 2
Space group P 6 2 c (No. 190)Template: room group / 190
Lattice parameters see crystal structure
Formula units Z  = 6
Frequent crystal faces {0001}, {10 1 0}
Physical Properties
Mohs hardness 4 to 4.5
Density (g / cm 3 ) 4.9 to 5.2
Cleavage indistinct according to (10 1 0), divisible according to (0001)
Break ; Tenacity uneven; brittle
colour wax to honey yellow, brick red to carmine red, reddish brown to dark brown
Line color White
transparency transparent to translucent
shine Glass gloss to fat gloss

Bastnäsite (English also Bastnaesite ) is the name for a group of minerals from the mineral class of " carbonates and nitrates " (formerly carbonates, nitrates and borates). All Bastnäsite crystallize in the hexagonal crystal system with the general composition (Ce, La, Nd, Y) [(F, OH) | CO 3 ], so they contain the rare earth metals cerium , lanthanum , neodymium and yttrium in addition to the carbonate complex from the group of lanthanides and fluorine or hydroxide ions as additional anions . The Bastnäsite are therefore also known as lanthanide fluorocarbonates .

In nature, due to the formation of mixed crystals , bastnasites are always found in connection with two or more of the rare earths. Currently recognized by the International Mineralogical Association (IMA) are only the end members of the mixed series with the following idealized composition, which are summarized as a bastnäsite group:

  • Bastnesite- (Ce) - Ce [F | CO 3 ]
  • Bastnesite (La) - La [F | CO 3 ]
  • Bastnesite (Nd) - Nd [F | CO 3 ]
  • Bastnesite- (Y) - Y [F | CO 3 ]
  • Hydroxylbastnesite (Ce) - Ce [(OH) | CO 3 ]
  • Hydroxylbastnesite- (La) - La [(OH) | CO 3 ]
  • Hydroxylbastnesite (Nd) - Nd [(OH) | CO 3 ]

Thorbastnesite (ThCa [F | CO 3 ] 2 · 3H 2 O) is also included in the bastnesite group .

Bastnäsite are mostly found in the form of granular to massive mineral aggregates , but also develop hexagonal crystals with a tabular to prismatic habit and a glass- to fat-like sheen . Depending on the composition of the mixed crystals, the color of the transparent to translucent crystals varies from wax to honey yellow, brick red to carmine red or reddish brown to dark brown. With a Mohs hardness of 4 to 4.5, bastnäsite is one of the medium-hard minerals that, like the reference minerals fluorite (4) and apatite (5), can be scratched with a pocket knife .

Along with monazite and xenotime, bastnesite is one of the most important ores for the extraction of rare earth metals .

Etymology and history

Bastnäsite was first discovered in 1838 in an ore mine near Bastnäs near the municipality of Skinnskatteberg in the Swedish province of Västmanland and described in 1841 by the French mineralogist Jean Jacques Nicolas Huot , who named the mineral after its type of locality .

During the analysis of the mineral, Huot determined that a large part of the cerium content has been replaced by lanthanum (cerium: lanthanum = 3: 2). In addition, in 1961 EE Vainshtein, LK Pozharitskaya and NV Turanskaya discovered another bastnasite representative with a dominant lanthanum content in the formula in the rare earth deposit "Belaya Zima" in the Siberian Sajan Mountains , which was accordingly designated as bastnasite (La). Due to the already recognized mixed crystal formation, the chemical formula of both minerals is also given in many reference works with (Ce, La) [F | CO 3 ] or (La, Ce) [F | CO 3 ].

Hydroxylbastnäsit- (Ce) was first discovered in 1962 in the Vuorijärvi massif (Vuoriyarvi) in the Russian-Finnish region of Karelia or in the so-called "Mochalin Log" near Kyschtym in the Urals and described in 1964 by AS Kirillov.

The discovery and first description of hydroxylbastnäsit- (La) and hydroxylbastnäsit- (Nd) followed in 1983 and 1985 by Z. Maksimović and G. Pantó, although the recognition of hydroxylbastnäsit- (La) by the IMA / CNMNC has not yet been confirmed, as the description was published without review by the CNMNC. As a type locality that apply here bauxite - deposit "Nissi" in the Greek region of Fthiotida ( Fthiotis ) and Niksic in Montenegro.

Bastnasite became more important after a substantial deposit was discovered in an old gold mine in Mountain Pass , California.

classification

In the meanwhile outdated, but still common 8th edition of the mineral classification according to Strunz , the bastnäsite group with the system no. V / C.07 to the common mineral class of "carbonates, nitrates and borates" and there to the department of "anhydrous carbonates with foreign anions ". In addition to the bastnasites and hydroxylbastnasites, the other members cebaite (Ce) , cordylite (Ce) , horváthite (Y) , huanghoite (Ce) , kozoite (La) , kozoite (Nd) , kukharenkoite ( Ce) , Kukharenkoit- (La) , Lukechangit- (Ce) , Micheelsenit , Mineevit- (Y) , Parisit- (Ce) , Parisit- (Nd) , Qaqarssukit- (Ce) , Reederit- (Y) , Röntgenit- ( Ce) , Synchisit- (Ce) , Synchisit- (Nd) , Synchisit- (Y) and Zhonghuacerit- (Ce) to this group.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns the bastnäsite group to the newly defined class of “carbonates and nitrates” (the borates now form their own class), but there also in the section of “carbonates with additional anions; without H 2 O “. However, this is further subdivided according to the predominant metals in the compound and the bastnasite group with system no. 5.BD.20a can be found in the subsection “With rare earth elements (REE)” and, in addition to the bastnasites and hydroxylbastnesites, only thorbastnesite belongs to this group.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the bastnasite group, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the division of “carbonates - hydroxyl or halogen”. The bastnäsite (system no. 16a.01.01 ) and hydroxylbastnäsite (system no. 16a.01.02 ) each form a separate subgroup within the sub-section " Carbonates - hydroxyl or halogen in the bastnäsite / synchism / parisite groups ".

Crystal structure

The Bastnäsite crystallize hexagonally in space group P 6 2 c (space group no.190) with the following lattice parameters : Template: room group / 190

  • Bastnesite- (Ce) - a  = 7.12  Å and c  = 9.76 Å ° and 6 formula units per unit cell .
  • Bastnesite- (La) - a  = 7.09 Å and c  = 9.718 Å ° and 6 formula units per unit cell.
  • Bastnesite- (Y) - a  = 6.57 Å and c  = 9.48 Å ° and 6 formula units per unit cell.

The hydroxyl bases also crystallize hexagonally, but in space group P 6 (space group no. 174) with the following lattice parameters: Template: room group / 174

  • Hydroxylbastnesite (Ce) - a  = 12.4112 Å and c  = 9.8511 Å ° and 6 formula units per unit cell.
  • Hydroxylbastnesite- (Nd) - a  = 12.32 Å and c  = 9.88 Å ° and 6 formula units per unit cell.

Education and Locations

Bastnäsite forms mainly magmatic in carbonatites and pegmatites , but can also be metasomatous through contact . As Begleitminerale occur including various Allanite , Cerite , Fluocerite , Gagarinite , Synchysite and Pari site and Cerianit- (Ce) , fluorite , hematite , microcline and quartz .

So far (as of 2013) around 500 sites for bastnäsite and around 20 sites for hydroxylbastnäsite are known to be known. The main sites of bastnäsite are, however, Bayan Obo in China, Mountain Pass in California and Madagascar. The largest known enrichment of rare earth minerals in the world, the Sulphide Queen deposit in the Mountain Pass District in California , contains, among other things, bastnasite, which is bound to carbonatite veins and potash-rich intrusions .

Known due to unusual bastnäsite finds are, among others, Andakatany in the Amoron'i Mania region on Madagascar and Karonge (Gakara, Bujumbura) in Burundi , where crystals up to 20 and 10 cm in size appeared. Nicely formed and partially transparent bastnäsite crystals were found primarily in the Trimouns talc mine near Luzenac in France and on Zagi Mountain ( Zegi Mountain ) in the so-called tribal areas under federal administration (FATA) in Pakistan.

Bastnäsite is chemically unstable to weathering, whereby the oxide is dissolved and combined with existing phosphates (formation of monazite).

  • Hexagonal prismatic, honey yellow bastnäsite (Ce) crystal from Zagi Mountain ( Zegi Mountain ), Mulla Ghori, FATA , Pakistan ( overall size : 5.0 × 4.2 × 2.8 cm)

  • Hexagonal tabular, reddish translucent bastnäsite (Ce) crystal from the same site (size: 1.5 × 1.5 × 0.3 cm)

  • Brownish bastnäsite (La) rosettes in a calcite druse from the Jones Mill quarry, Magnet Cove, Hot Spring County , Arkansas, USA (field of view 3 mm)

Use and processing

element typical share
Lanthanum 33.2%
cerium 49.1%
Neodymium 12 , 0 %
Praseodymium 04.3%
Samarium 8000 ppm
Gadolinium 1700 ppm
Europium 1200 ppm
Dysprosium 0310 ppm
Terbium 0160 ppm
holmium 0050 ppm
Erbium 0035 ppm
Thulium 0008 ppm
ytterbium 0006 ppm
lutetium 0001 ppm

Since the 1960s, a large part of the world production of lanthanides has been extracted from the Bastnäsites . The following table shows a typical distribution of rare earth metals using the example of bastnäsite (Ce), although the exact composition may vary depending on the site.

Bastnesite is usually digested with acid. Treatment of the unroasted ore with concentrated sulfuric acid releases hydrogen fluoride and forms insoluble lanthanide sulphates, which can then be dissolved in cold water and processed further. When the unroasted ore is treated with dilute sulfuric acid, the lanthanoids are dissolved as sulfates and the fluorides are bound as a stable cerium IV complex. The extraction then requires the separation of the fluorides by treatment with sodium hydroxide solution. When the unroasted ore is treated with hydrochloric acid at approx. 100 ° C, most of the lanthanoids are dissolved as chlorides, but leave behind an insoluble lanthanoid-fluoride residue. The latter has to be converted into hydroxides by treatment with caustic soda before further processing is possible.

If the bastnäsite ore is roasted beforehand in order to remove carbon dioxide and to oxidize the cerium present, the main proportion of lanthanides can also be separated by treatment with hydrogen chloride, but the remaining residue still contains significant amounts of insoluble lanthanides and fluorides, as well as cerium IV- oxide. By treating calcined bastnesite with 57% nitric acid, lanthanoids are separated from sparingly soluble silicon dioxide and barium sulfate. The lanthanides are then obtained from the filtrate by extraction with tri-n-butyl phosphate.

literature

  • Bastnäsite- (Ce) . 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; 65 kB ; accessed on March 31, 2018]).
  • Bastnäsite- (La) . 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; 63 kB ; accessed on March 31, 2018]).
  • Bastnäsite- (Nd) . 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; 271 kB ; accessed on March 31, 2018]).
  • Bastnäsite- (Y) . 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; 66 kB ; accessed on March 31, 2018]).
  • Hydroxylbastnäsite- (Ce) . 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; 66 kB ; accessed on March 31, 2018]).
  • Hydroxylbastnäsite- (Nd) . 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; 65 kB ; accessed on March 31, 2018]).

Web links

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

Individual evidence

  1. ↑ 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.  299 .
  2. ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  549-550 .
  3. ↑ a b c d e f g h IMA / CNMNC List of Mineral Names (November 2012; PDF 8.6 MB; Note: Formula representation: crystal chemical structural formula according to Strunz)
  4. ^ Daniel Lundberg: The Coordination Chemistry of Solvated Metal Ions in DMPU , Doctoral thesis, Swedish University of Agricultural Sciences, Uppsala 2006 ( PDF 9.2 MB; p. 22 )
  5. ↑ JJN Huot: Genre. Lanthanum. 2 Espèce, Bastnaesite . In: Manuels-Roret. Nouveau Manuel Complet de Minéralogie . Première Partie, Paris 1841, p. 296–296 ( rruff.info [PDF; 553 kB ; accessed on March 31, 2018]).
  6. ↑ Bastnäsite- (La) . 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; 63  kB ; accessed on March 31, 2018]).
  7. ↑ AS Kirillov: Hydroxyl bastnäsite, a new variety of basnäsite . In: Doklady Akademii Nauk SSSR Earth Science Sections . tape 159 , 1964, pp. 93–95 ( rruff.info [PDF; 194 kB ]).
  8. ↑ Mindat - Mindat-Hydroxylbastnäsite- (La)
  9. ↑ Mindat - Hydroxylbastnäsite- (Nd)
  10. ↑ a b Bailar et al.: Comprehensive Inorganic Chemistry (5 volumes) . Pergamon Press, Oxford 1973, ISBN 0-08-017275-X .
  11. ↑ American Mineralogist Crystal Structure Database - Bastnäsite- (La) (I. Oftedal, 1931)
  12. ↑ American Mineralogist Crystal Structure Database - Hydroxylbastnäsite- (Ce) (H. Yang, RF Dembowski, PG Conrad, RT Downs, 2008)
  13. ↑ American Mineralogist Crystal Structure Database - Hydroxylbastnäsite- (Nd) (N. Christensen, 1973)
  14. ^ Mindat - Bastnäsite
  15. ^ Mindat - Hydroxylbastnäsite
  16. ↑ a b CK Gupta, N. Krishnamurthy: Extractive metallurgy of rare earths . CRC Press, Boca Raton Fla 2005, ISBN 0-415-33340-7 .
  17. ↑ a b Occurrence of lanthanoids - Uni Bielefeld
  18. ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 124 .