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.

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.