Quarterly Crystal: Triplite in Topaz
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).
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.
