Micro-World Gems & Gemology, Summer 2018, Vol. 54, No. 2

A Horse-Shaped Inclusion in Pink Sapphire from Mozambique

Raman analysis identified the horse-shaped inclusion as phlogopite mica.
The horse-shaped inclusion of phlogopite mica identified by Raman analysis. Photomicrograph by Charuwan Khowpong; field of view 2.40 mm.

Recently, GIA’s Bangkok lab received a 0.58 ct pink sapphire with a unique inclusion. Microscopic observation revealed needles, platelets, and particles, all of which are common inclusions found in Mozambican ruby and pink sapphire. The most interesting inclusion was found near the stone’s girdle. The crystal, which resembled a horse (see above), was identified as phlogopite. The most common mineral inclusions in Mozambican rubies are crystals of amphibole and mica (V. Pardieu et al., “Rubies from the Montepuez area (Mozambique),” 2013; V. Pardieu et al., “GIA lab reports on low-temperature heat treatment of Mozambique ruby,” 2015). Most of the mica inclusions are margarite or muscovite, typically with a lighter color and pseudohexagonal shape. Phlogopite is another end member of the mica series, but with a very different chemical composition from muscovite. To our knowledge, phlogopite mica has not been reported in Mozambican rubies or pink sapphires

Charuwon Khowpong is an analytics technician at GIA in Bangkok.