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Bastnäsite



Bastnäsite
CategoryCarbonate mineral
Chemical formula(Ce,La,Y)CO3F
Identification
ColorHoney-yellow, reddish brown
Crystal habitTabular to equant striated crystals, also granular, massive
Crystal systemHexagonal - Ditrigonal Dipyramidal
TwinningDauphine law, Brazil law and Japan law
CleavageImperfect to indistinct
FractureUneven
Mohs Scale hardness4 - 5
LusterVitreous - greasy
Refractive indexnω = 1.717 - 1.722 nε = 1.818 - 1.823
Optical PropertiesUniaxial (+)
Birefringenceδ = 0.101 max.
PleochroismFaint
StreakWhite
Specific gravity4.95 - 5.0
DiaphaneityTransparent to translucent
Other CharacteristicsStrongly piezoelectric; dark red cathodoluminescence
References[1][2][3]

The mineral bastnäsite is one of a family of three carbonate-fluoride minerals. There is bastnäsite-(Ce) with a formula of (Ce, La)CO3F. There is bastnäsite-(La) with a formula of (La, Ce)CO3F. There is also bastnäsite-(Y) with a formula of (Y, Ce)CO3F. Most bastnäsite is bastnäsite-(Ce), and cerium is by far the most common of the rare earths in this class of minerals. Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare earth elements.

Additional recommended knowledge

Bastnäsite was first described in 1841 from and named for the Bastnas Mine in the Riddarhyttan district, Vastermanland, Sweden.[2]

Bastnäsite occurs in alkali granite and syenite and in associated pegmatites. It also occurs in carbonatites and in associated fenites and other metasomatites.[1][4]

References

  1. ^ a b http://rruff.geo.arizona.edu/doclib/hom/bastnasitece.pdf Handbook of mineralogy
  2. ^ a b http://webmineral.com/data/Bastnasite-(Ce).shtml Webmineral
  3. ^ http://www.mindat.org/min-560.html Mindat
  4. ^ http://mineral.galleries.com/minerals/carbonat/bastnasi/bastnasi.htm Mineral Galleries
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Bastnäsite". A list of authors is available in Wikipedia.
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