bastnaesite
bastnaesite crystal from Pakistan
crystal of bastnaesite from Lazenac in Arriege, France
bastnaesite crystal from Zagi in Pakistan
liquid like inclusions, healing fissures
Detailed sheet
bastnaesite
It takes its name from the mine Bastnas Riddarhyttan in Vastmanland in Sweden where it was discovered. There are three varieties of bastnaesite based on the predominant “rare earth element” (rare metallic chemical elements) in it. Here lanthanum is the dominating but also cerium can dominate or yttrium. It has a color changing effect depending on the nature of light that illuminates it, yellow with white light and orange in incandescent light.
CHEMICAL CHARACTERISTICS
(La,Ce)[CO3](F,OH)
carbonate - fluoride of rare earth elements
PHYSICAL CHARACTERISTICS
Main color
yellow
Other colors
brown, orange
Color of streak
white
Luster
resinous
Hardness
4.0 to 4.5
Density
4.78 to 5.20
Cleavage
indistinct
Fracture
uneven
small flat portions observed on the fracture
OPTICAL PROPERTIES
Transparency
translucent, transparent
Refractive index
1.720 - 1.820
Double refraction
0.100
strong, positive uniaxial
visible double refraction
Yes
Dispersion
aucune
Pleochroism
absent
Number of colors
1
brown bastnaesite spectrum system
orange bastnaesite spectrum system
Fluorescence
none
CRYSTALS PROPERTIES
tabular hexagonal
crystals system
hexagonal
OTHER INFORMATIONS
APPROACHING GEMS
Exploited
sites
It is found worldwide but well-formed crystals and gems are rare.
The most productive deposits are found in the Zagi Mountains in Pakistan and at Shiwaro in the Kunar Valley in Afghanistan.
In France it is found in the Talc mine of Luzenac in Arriege.
use in jewelry
Since 1998, it has been found in a quality that can be cut, its beautiful red or orange color makes it attractive, it is faceted for collection but too fragile to be used in jewelry.
Other
Gems
Venez visitez
notre site web
voillot-joaillier.fr
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