Micro-World Gems & Gemology, Spring 2022, Vol. 58, No. 1

Vietnamese Skyline

Iridescent needles in a Vietnamese red spinel resemble a skyline.
Hogbomite-filled dislocations in a Vietnamese spinel. Photo by Wimon Manorotkul; vertical field of view 4 mm.

In the red spinel from Vietnam’s Luc Yen district in the figure above, layers of iridescent needles stretch skyward like a futuristic skyline from a science fiction novel. Such hogbomite-filled dislocations are a common sight in red, pink, and blue spinel from Vietnam. According to Gübelin and Koivula (Photoatlas of Inclusions in Gemstones, Volume 2, Opinio Verlag, Basel, Switzerland, 2005), hogbomite (Mg,Fe)2(Al,Ti)5O10 is found in spinel via isomorphous replacement.

Wimon Manorotkul is a gemologist and co-founder of Lotus Gemology in Bangkok.