Micro-World Gems & Gemology, Summer 2016, Vol. 52, No. 2

Quarterly Crystal: Triplite in Topaz

Pinkish orange inclusion in topaz.
Figure 1. A pinkish orange inclusion dominates the interior of this 20.58 ct unpolished topaz crystal from Pakistan. Photograph by Kevin Schumacher.

The transparent colorless 20.58 ct topaz crystal in figure 1 clearly hosts a prominent translucent pinkish orange inclusion. The topaz, from Biensa in Braldu Valley, Gilgit-Baltistan, Pakistan, was acquired from Dudley Blauwet of Mountain Minerals International (Louisville, Colorado). The bodycolor of the inclusion suggested that it might be either of two equally rare pegmatitic phosphates, triplite or väyrynenite, that are known to occur in pegmatites in that part of the world (figure 2).

The inclusion is identified as triplite.
Figure 2. A combination of Raman and EDXRF analysis served to identify the inclusion as triplite. The inclusion is seen here using brightfield and fiberoptic illumination. Photomicrograph by Nathan Renfro; field of view 9.39 mm.

Laser Raman microspectrometry was able to narrow the inclusion’s identity to these two suspected phosphates. Triplite and väyrynenite have very similar Raman peak patterns, and the topaz host masked some of the significant peaks needed to conclusively separate the two minerals. Since triplite contains iron and väyrynenite does not, focused energy-dispersive X-ray fluorescence (EDXRF) analysis was used to examine the inclusion’s chemical composition. Results indicated the presence of iron, identifying the inclusion as triplite. This marks the first time triplite has been reported as an inclusion in topaz.

John I. Koivula is the analytical microscopist at GIA in Carlsbad, California.