Bastnäsite

Bastnäsite is named after its discovery locality at Bastnäs, Ridar-hyttan district, Västmanland, Sweden.

Bastnasite is found as dark orange brown to brown crystals.

Gem rough and cut stones are rare.

Bastnäsite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 
 

Bastnäsite Gemstones by Size

This table shows distribution of Bastnäsite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.47 cts
Heaviest:6.22 cts
Average:2.16 cts
Total photos:19
Do you have a larger Bastnäsite? Why not upload a photo?
0.47ct to 1.05ct1.05ct to 1.62ct1.62ct to 2.20ct2.20ct to 2.77ct2.77ct to 3.35ct3.35ct to 3.92ct3.92ct to 4.50ct4.50ct to 5.07ct5.07ct to 5.65ct5.65ct to 6.22ct
General Information
Other Names/Trade Names:
Chemical Formula
(Ce,La)(CO
 
3
)F
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Photos of natural/un-cut material from mindat.org
Physical Properties of Bastnäsite
Mohs Hardness4 to 4.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Specific Gravity4.78 to 5.20
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Cleavage QualityDistinct,Poor
Arthur Thomas, Gemstones (2009) Distinct - basal, Poor - prismatic
FractureUneven
Arthur Thomas, Gemstones (2009)
Optical Properties of Bastnäsite
Refractive Index1.72 to 1.82
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical CharacterUniaxial/+
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Birefringence0.100
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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PleochroismWeak
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Orange-brown, brown
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTransparent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous,Pearly
Arthur Thomas, Gemstones (2009)
Crystallography of Bastnäsite
Crystal SystemHexagonal
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
HabitShort prisms, Tabular rounded
Arthur Thomas, Gemstones (2009)
Geological Environment
Where found:Occurs in bauxite deposits, carbonatites and rarely in unusual granites. Sometimes in hydrothermal sources.
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Bastnäsite information at mindat.org
Copyright © Jolyon & Katya Ralph 1993-2014. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.