Micro-World Gems & Gemology, Fall 2021, Vol. 57, No. 3

Tourmaline in Paraíba Tourmaline

Tourmaline crystal in a Brazilian tourmaline.
A tourmaline inclusion in Brazilian Paraíba tourmaline. Photomicrograph by Suwasan Wongchacree; field of view 4.8 mm.

The authors examined the 3.21 ct Paraíba tourmaline shown above. The stone was moderately included with fine thread-like trichite fluid inclusions, growth tubes, and many fractures. Growth tubes are often open on one or both ends and may contain epigenetic minerals encapsulated within such as limonite, cookeite, hematite, prosopite, and tourmaline (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, pp. 763, 764, and 780–781). In this tourmaline, we observed a long prismatic crystal that had a morphology consistent with tourmaline, which was confirmed using Raman spectroscopy. This offered an interesting example of a gem tourmaline that contained a tourmaline inclusion.

Sudarat Saeseaw is senior manager of colored stone identification, and Suwasan Wongchacree is a lapidary analyst, at GIA in Bangkok.