grandidierite
grandidierite crystal from Marotrano in Madagascar
Detailed sheet
grandidierite
Discovered at Andrahomana, near Fort Dauphin in Madagascar.
Its name honors the French explorer Alfred Grandidier (1836-1912).
CHEMICAL CHARACTERISTICS
(Mg,Fe)Al3(BO3)[SiO4]O2
aluminum boro - silicate
PHYSICAL CHARACTERISTICS
Main color
blue
Other colors
green
blue - green
Color of streak
white
Luster
vitreous
Hardness
0.0 to 0.0
Density
0.00 to 0.00
Cleavage
perfect
Fracture
uneven
uneven fracture with small flat parts
OPTICAL PROPERTIES
Transparency
opaque, translucent
Refractive index
1.590 - 1.623
Double refraction
0.033
definite, biaxial (-)
visible double refraction
No
Dispersion
++
Pleochroism
definite
Number of colors
3
blue - green, light green, colorless
Fluorescence
none
CRYSTALS PROPERTIES
dipyramidal
crystals system
orthorhombic
OTHER INFORMATIONS
APPROACHING GEMS
Exploited
sites
It is found in Gordonia, South Africa, Maratakka in Surinam, in Wyoming at Morton Pass in the U.S., in Germany, Norway and Australia.
use in jewelry
it is cabochon cut or emerald cut in levels, it’s a collection stone
Other
Gems
Venez visitez
notre site web
voillot-joaillier.fr
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