on matrix 138 gr. 55 x 50 mm. individual
crystal: 20 x 18.5 mm. Origin Madagascar
Hardness: 7.5 /
Refractive index: 1.71 / Density
3.40 to 3.58 / Mg2Al4[O6|SiO4]
Sapphirine: Monoclinical magnesium aluminosilicate of dark blue color.
pseudo hexagonal contour. This
mineral indicates a granulite facies, and appears in amphibolites, associated
with corundum, but it also meets in aluminous and magnesian metamorphized
rocks, low in silica.