Sapphirine

Sapphirine is a rare mineral, a silicate of magnesium and aluminium. Named for its sapphire-like colour, sapphirine is primarily of interest to researchers and collectors: well-formed crystals are treasured and occasionally cut into gemstones. Sapphirine has also been synthesized for experimental purposes via a hydrothermal process.

Typical colours range from light to dark sapphire blue, bluish to brownish green, green, and bluish or greenish gray to black; less common colours include yellow, pale red, and pink to purplish pink. Sapphirine is relatively hard (7.5 on Mohs scale), usually transparent to translucent, with a vitreous lustre.

Source: en.wikipedia.org/wiki/Sapphirine

Sapphirine Properties

Chemical Composition: 
Complex Magnesium Aluminium Silicate - MgAl2SiO6
Colors / Varieties: 
Pale to dark blue green, purplish pink.
Crystal System / Forms: 
Monoclinic System / Indistinct tabular crystals, fibrous to columnar aggregates.
Hardness: 
7 - 7.5
Specific Gravity: 
3.40 - 3.50
Cleavage / Fracture: 
Indistinct / Conchoidal fracture
Optic Character: 
Anisotropic, D.R.; Biaxial negative / positive
Lustre: 
Vitreous
Refractive Index / Birefringence: 
1.704 - 1.710 / 0.006
Pleochroism: 
Strong. Light Blue, Blue, Dark Blue (Shades of body color)
Magnification: 
Phase and crystal inclusions, fingerprints.
U.V. Fluorescence: 
Inert.
Spectrum: 
Color varies with iron percentage.
Cause of Color: 
Not characteristic.
Simulants (with separation tests): 
Sapphire (optic figure, R.I., S.G., inclusions), Natural Spinel (optic character), Kyanite (birefringence, S.G., inclusions)
Geological Occurrence: 
In schists, gneiss, contact metamorphism.
Sources: 
Sri Lanka, Greenland, Madagascar.
Cuts & Uses: 
Facetted cuts.