微观世界 Gems & Gemology, Summer 2018, Vol. 54, No. 2

Microlite Crystals in Topaz from Pakistan


有着微晶石内含物的拓帕石,产自巴基斯坦。
Figure 1. A 16 mm topaz crystal and an 8.69 ct faceted topaz, both with microlite inclusions, from Pakistan. Photo by J. Hyršl.

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.

Microlite crystal in a topaz from Pakistan.
Figure 2. A microlite crystal, measuring 1 mm across, in a topaz from Pakistan. Photo by J. Hyršl.

Jaroslav Hyršl is a mineralogist and author based in Prague.