These samples of brownish orange uvite tourmaline were reportedly mined from Kunar Province, Afghanistan. The equant, well-formed crystals are found in a soft, white, talc-like matrix. The two cut stones weigh 0.59 and 1.46 ct. Courtesy of Intimate Gems; photo by Maha Tannous.

In July 2002, Sir-Faraz (“Farooq”) Hashmi of Intimate Gems, Jamaica, New York, sent GIA some brownish orange samples from Afghanistan that were tentatively identified as either tourmaline or bastnäsite. Included in this donation were two faceted stones (0.59 and 1.46 ct) that were cut for our research by John Bailey (Klamath Falls, Oregon), several loose crystals, and two specimens of the brownish orange crystals in a white, talc-like matrix (see figure). Mr. Hashmi was told by Gaus-ud-din, an Afghan partner, that the material was mined from the “Wata Poore” area in Konar Province. Reportedly a few dozen kilograms of the material has been mined, although production has slowed in recent months due to the unrest in the region.

The crystals were equant and lacked the striations on their prism faces that are typically seen on tourmaline from Afghanistan and elsewhere, and the mineralogy of the matrix material indicated that it was not derived from a granitic pegmatite. Nevertheless, standard gemological properties obtained on the two faceted stones indicated that they were tourmaline (i.e., uniaxial negative optic character, R.I.—1.620–1.641, birefringence—0.021, and S.G.—2.99 and 3.04). Microscopic examination revealed abundant mineral inclusions of colorless to white, anhedral, birefringent particles; partially healed fractures; and “feathers.” A few dark brown (nearly black), transparent inclusions also were present. The stones were inert to long-wave UV, and showed a chalky greenish orange fluorescence of moderate intensity to short-wave UV radiation.

To better characterize these unusual tourmalines, one of the crystals was analyzed by electron microprobe at the University of New Orleans. The sample proved to be uvite, a Ca-Mg tourmaline that is uncommon in facetable quality. The six analyses revealed a rather homogeneous composition, with an appreciable dravite component (as shown by the presence of 1.35 wt.% Na₂O). In addition, the analyses showed an average of 1.14 wt.% TiO₂, 0.06 wt.% FeO, and 0.50 wt.% F. Polarized visible-range spectroscopy of one sample showed that the brownish orange color is due to a combination of Fe²⁺–Ti⁴⁺ intervalence charge transfer and Fe²⁺ (G. Rossman, pers. comm., 2003).