neptunite
neptunite crystal from San Benito in U.S.
Detailed sheet
neptunite
Discovered by the mineralogist Flink in 1893, it was named Neptune, the God of the Sea for the Romans, as it was discovered on the same site, in association with aegirine, the scandinavian name of the God of the sea
CHEMICAL CHARACTERISTICS
KNa2Li(Fe,Mn)2Ti2[Si8O24]
manganese and iron alkaline titanosilicate
PHYSICAL CHARACTERISTICS
Main color
black
Other colors
brown, red
very dark
Color of streak
brown
Luster
vitreous
Hardness
5.0 to 6.0
Density
3.19 to 3.25
Cleavage
perfect
Fracture
conchoidal
OPTICAL PROPERTIES
Transparency
opaque, translucent
very rarely transparent
Refractive index
1.690 - 1.735
Double refraction
0.028
difficult to observe biaxial positive
visible double refraction
No
Dispersion
++
Pleochroism
definite
Number of colors
2
yellow, orange red
Fluorescence
none
CRYSTALS PROPERTIES
prismatic
crystals system
monoclinic
OTHER INFORMATIONS
APPROACHING GEMS
Exploited
sites
It is found associated with benitoite, in San Benito, California and other deposits in the United States and Canada. It is present in Brazil, Russia, Mongolia, Tajikistan, Australia, Ireland, Greenland.
use in jewelry
often of a very dark color, it is cut in facets. It’s a collection stone
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