Bastnaesite

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A rare gem, bastnaesite is named after the Swedish locality where it was originally discovered in 1841, the Bastnas mines. Color can range from honey yellow to reddish brown and crystals vary from transparent to translucent in appearance. Valued by industry as a source of rare-earth elements, bastnaesite is rare, but has been found in small quantities throughout the world. It is difficult to cut because it is a relatively soft mineral, however, its high refractive index, combined with its rarity, make it an exciting gem to own.

Bastnaesite Polished
Bastnaesite Classification
Common Name Bastnaesite
Species Bastnaesite
Bastnaesite Optical Properties
Transparency Transparent
Dispersion Strength: None
Refractive Index Over The Limit 1.717-1.823
Birefringence 0.101
Optic Character Uniaxial
Optic Sign Positive
Polariscope Reaction Doubly Refractive (DR)
Pleochroism Unobservable
Bastnaesite Characteristic Physical Properties
Hardness 4-4.5
Specific Gravity 4.780-5.200
Toughness Poor
Luster Vitreous, Pearly
Stability Poor
Fracture Uneven
Cleavage Poor, in one direction
Bastnaesite Chemistry & Crystallography
Chemical Name cerium carbonate fluoride
Chemical Formula (Ce,La)(CO3)F
Crystal System Hexagonal
Chemistry Classification Carbonate

Bastnaesite Colors

  • Brown Bastnaesite Brown
  • Yellow Bastnaesite Yellow
  • Orange Bastnaesite Orange

Bastnaesite Spectra

Bastnaesite Spectra
BASTNAESITE. (ε ray)

Color due to rare earths. A cerium mineral showing a neodymium spectrum which will vary in strength according to size and intensity of color of specimen. As you rotate a polarizing filter the line in the red will now become a weaker doublet and the line in the blue a broader single line.

Bastnaesite Spectra
BASTNAESITE. (unpolarized)

Color due to rare earths. A cerium mineral showing a neodymium spectrum which will vary in strength according to size and intensity of color of specimen. As with all brownish orange stones resolution of lines in the deep blue to violet areas is difficult to determine

Bastnaesite Spectra
BASTNAESITE. (ω ray)

Color due to rare earths. A cerium mineral showing a neodymium spectrum which will vary in strength according to size and intensity of color of specimen. Optical orientation will determine the hue and exhibit a subtle change in the spectrum pattern. In the darker ordinary ray, the doublet in the red at about 675nm. strengthens to become a broader and darker line, whereas, the line in the blue at about 485nm.is now seen as a weaker doublet.

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Alternate Names

BastnSite

Countries of Origin

Pakistan

History

Bastnaesite, a mineral, is not rare. However, In gem quality, it is extremely rare. Bastnaesite is named after the Bastnas mines in Sweden, where it was originally discovered in 1841. It's characterized by warm colors ranging from honey yellow to reddish brown. Its crystals vary from transparent to translucent in appearance. Bastnaesite is valued by industry as a source of rare-earth elements. Gem-quality bastnaesite has been found in small quantities throughout the world. It is difficult to cut because it is a relatively soft mineral, however, its high refractive index (i.e., high brilliance and fire), combined with its rarity, make it an exciting gem to own.

Care

This stone is a 4 - 5 on the Mohs scale, so be sure to treat it with care. Other stones will scratch it, so it's wise to store it separately or wrapped in a protective cloth.

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Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.