Microlite Crystals in Topaz from Pakistan
Microlite, NaCaTa2O6(OH), is a typical mineral of highly developed lithium pegmatites, known from many localities worldwide. It always forms yellow to orange octahedral crystals. It was already known as inclusions in quartz from Pakistan (J. Hyršl and G. Niedermayr, “Einschlüsse im ‘Allerweltsmineral’ quarz,” Mineralien-Welt, Vol. 18, No. 2, 2007, pp. 44–55), but much more beautiful are microlite inclusions in topaz (figure 1), examples of which were sold in Tucson in January 2018. Shigar Valley in northern Pakistan was reported as the locality. Both minerals were confirmed by Raman spectroscopy.
Topaz forms loose, very light brown crystals up to about 2 cm, and microlite forms sharp transparent orange octahedrons in sizes up to about 1.5 mm. The inclusions grew both on the surface and inside the topaz crystals (figure 2). Several topaz crystals were faceted, and the stones host some of the most aesthetically pleasing inclusions found during the several last years.