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Bastnäsite-(Ce)
Current inventory:  0 gems
 

Bastnäsite

  
Bastnäsite is named after the Bastnäs mine, Riddarhyttan, Skinnskatteberg, Västmanland, Sweden where it was originally discovered.

Discovered in 1841;   IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

Ce(CO3)F

 

Cerium Carbonate Fluoride

Molecular Weight:

219.12 gm

Composition:

Cerium

63.94 %

Ce

74.90 %

Ce2O3

 

Carbon

5.48 %

C

20.08 %

CO2

 

Oxygen

21.90 %

O

 

 

 

Fluorine

8.67 %

F

8.67 %

F

 

-

- %

F

-3.65 %

-O=F2

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/C.07-30

Nickel-Strunz 10th Ed. ID:

5.BD.20a

 

5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H
2O
D : With rare earth elements (REE)

Related to:

Bastnäsite Group. Cerium analogue of Bastnäsite-(La) and Bastnäsite-(Y). Fluorine analogue of Hydroxylbastnäsite-(Ce). Bastnäsite-(Ce)-Hydroxylbastnäsite-(Ce) Series. 4H, 6R, 3R polytypes.

Members of Group:

Bastnäsite Group: Bastnäsite-(Ce), Bastnäsite-(La), Bastnäsite-(Y)

Varieties:

None

Synonyms:

Bastnaesite, Basic Fluocerine, Basikfluorcerium, Basiskfluor-cerium, Bastnaesite-(Ce), Buszite, Hamartite, Hemartite, Hydrocerite (of Glocker), Hydrofluocerite, Kischtimite, Kischtim-Parisite, Kyshtymoparisite, Sub-fluate of cerium

 

 

Crystal Data

   

   

Crystallography:

Hexagonal - Ditrigonal Dipyrimidal

Crystal Habit:

Commonly in tabular to equant crystals, may be modified, horizontally striated, may be elongated, commonly in syntaxic intergrowth with röntgenite-(Ce), synchysite-(Ce), parisite-(Ce), or cordylite-(Ce), to 20 cm; granular, massive.

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

Imperfect on {1011}, Indistinct on {0001}

Fracture:

Uneven

Tenacity:

Brittle

Moh's Hardness:

4.0 - 4.5

Density:

4.90 - 5.20 (g/cm3)

Luminescence:

Dark red Cathodoluminescence

Radioactivity:

Weak; GRapi = 60,386.61 (Gamma Ray American Petroleum Institute Units)

Other:

Strongly Piezoelectric. Soluble in strong, hot acids. May be found as pseudomorphs after Fluocerite or Tscheffkinite.

 

 

Optical Properties

   

   

Color:

Wax Yellow, Honey Yellow, Reddish Brown

Transparency:

Transparent to Translucent

Luster:

Vitreous to Greasy, Pearly

Refractive Index:

1.717 - 1.823  Uniaxial ( + )

Birefringence:

0.1010

Dispersion:

0.013

Pleochroism:

Weak; faintly pleochroic when absorption E is greater than O.

 

 

Occurances

   

   

Geological Setting:

The most abundant REE-bearing mineral, typically hydrothermal, although primary igneous occurrences are known. In granite and alkali syenites and pegmatites; in carbonatites; in contact-metamorphic deposits; rarely as a detrital mineral in placers.

Common Associations:

Allanite-(Ce), Cerianite-(Ce), Cerite-(Ce), Fluocerite-(Ce), Fluorite, Parisite-(Ce), Synchysite-(Ce).

Common Impurities:

None

Type Locality:

Bastnäs mines, Riddarhyttan, Skinnskatteberg, Västmanland, Sweden

Year Discovered:

1841

View mineral photos:

Bastnäsite mineral photos and locations

 

 

Unusual Gem Categories

   

   

 

Piezoelectric Gems

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Bastnäsite (also spelled Bastnaesite) is an extremely rare gem and one of the few rare earth element (REE) carbonate minerals. Bastnäsite may be weakly radioactive as defined in
49 CFR 173.403 (greater than 70 Bq/gram) due to the presence of the rare earth element (REE) Cerium (64%). Bastnäsite and Monazite both contain Cerium (Ce) and are the two largest sources of Cerium. Gems are usually small and moderately included.

Bastnäsite is one of the unusual minerals that exhibit the piezoelectric effect. Piezoelectricity is the ability of some mineral crystals to generate a voltage in response to applied mechanical stress such as an external pressure. Piezoelectricity was discovered in 1880 by French physicists, brothers Jacques and Pierre Curie.

Bastnäsite distribution: Shinwaro, Kunar Province, Afghanistan; Mont Saint-Hilaire, Quebec, Canada; Andakatany, Ambatofangehana, Madagascar; Zegi Mountain, Fata, Pakistan; Karonge, Burundi; Wigu Hill, Tanzania; Nkombwa Hill, Zambia; and several locations in the USA including near Stove Mountain, in the St. Peters Dome area, and at Crystal Park, near Pikes Peak, El Paso County, Colorado.
 

  
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