STUDY OF THE CHEMICAL ELEMENTS COMPOSING THE COLORING ROLLS OF AMBONDROMIEHY SAPPHIRE: ANIVORANO COMMON IN THE DIANA REGION (MADAGASCAR)

Mineral Resource

Ambondromifehy, Maromokotra quarry, is located in the far north of Madagascar. This work involved carrying out gemological, sapphire chemical and paragenetic studies in this area. Gem corundums are extracted from alkaline basalt environments, secondary deposits in the north of the country (sapphire site). It is rare that the sapphires from Ambondromifehy, quarries of Maromokotra, have a uniform coloring. In our study area, the majority of sapphire is two-tone; The hexagonal dipyramid is the main color of sapphire. It is obvious that the three samples of sapphire taken from these quarries are truly corundum. It follows the gemmological characteristics close to most sapphire having density = 3.98 to 3.99, shock resistance as well as its very bright shine having refractive index: IR = 1.76 to 1.77 with birefringence = 0.009, negative uniaxial. Their transparency and translucency are remarkable. Iron, titanium, and chromium have been proven to be the main culprits in discoloration. We have argued that iron and titanium are predominant in sapphire production in our study region. It is likely that these elements come from the area where rutiles (TiO2) and ilmenites (FeTiO3) live. This is the reason why the Ambondromifehy sapphire has a blue color.

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