Benitoite
Refractive Index low
ne 1,802 - 1,805
Refractive Index high
no 1,756 - 1,757
Birefringence
0.043 - 0.047
Density
3.61 - 3.80
Polariscope
1 positive
Colours:
colourless, white, blue, pink, violet, orange, purple
Transparency:
Transparent
Pleochroism:
strong: colorless/blue, purple
UVL:
inert, colourless:dull red
UVS:
intens blue, white
Remarks:
pleo-stone, natrolite needles, high dispersion, check doubling facets.
Sometimes zoned.
Orange color commonly heated
Spectra:
Hardness:
6 - 6,5
Formula:
BaTiSi3O9
System:
Hexagonal
Rare?
3