Over the past few years, Afghanistan has become a significant source of gem-quality hessonite (grossular garnet), and some of the material has been found mixed into parcels with other orange to red stones from this region (see Summer 2001 Gem News International, p. 144). To our knowledge, the gemological properties of the Afghan hessonite have not been published, so we were interested to examine several faceted samples and mineral specimens that were recently loaned (and, in some cases, donated) to GIA by Sir-Faraz (“Farooq”) Hashmi of Intimate Gems, Jamaica, New York. In addition, Peter Lyckberg loaned six faceted examples for our examination. Mr. Hashmi reported that the hessonite comes from eastern Afghanistan; two known deposits are Munjagal in Kunar Province (producing roughly 1,500–2,000 kg/year of mixed grade) and Kantiwow, Nuristan Province (up to 5,000 kg/year). Most of the clean rough weighs 0.5–1 gram, in colors ranging from yellowish orange to red-orange. Although thousands of kilograms of this garnet have been produced, mining has waned in recent months due to lack of demand in the local market (i.e., in Peshawar, Pakistan) and the migration of miners to the kunzite deposits in the same region of Afghanistan.

The specimens we examined consisted of euhedral garnets that were commonly intergrown with anhedral massive quartz. This assemblage formed within massive garnet that was intergrown with quartz and, less commonly, a green mineral (probably epidote) and another white mineral (possibly wollastonite). This mineral association is typical of a skarn-type deposit formed by contact metamorphism of carbonate rocks by a granitic intrusion. The euhedral grossular crystals typically measured up to 1 cm in diameter, although some partial crystals of larger dimension (up to 4 cm) also were present. The crystals contained abundant fractures, but some had small areas that were transparent enough for faceting.

Three representative faceted stones (2.64–7.39 ct; figure 11) were selected for examination by one of us (EPQ), and the following properties were obtained: color—yellowish orange, orange, and red-orange; diaphaneity—transparent, R.I.—1.739 or 1.740; S.G.—3.63 or 3.64; weak to moderate ADR in the polariscope; and inert to both long- and short-wave UV radiation. Weak absorption bands at 430 and 490 nm were observed with a desk-model spectroscope. Microscopic examination revealed transparent near-colorless crystals (one of which was identified as apatite by Raman analysis), needles, “fingerprints,” stringers of particles, fractures, and straight and angular growth lines. One stone showed evidence of clarity enhancement. The R.I. values of these samples are slightly lower than those reported in the literature for hessonite (see R. Webster, Gems, 5th ed., rev. by P. G. Read, Butterworth-Heinemann, Oxford, 1994, pp. 201–202). Notably, the three Afghan samples did not show the roiled or oily appearance that is commonly seen in hessonite; nor was this feature noted upon further examination of several additional faceted stones.

Brendan M. Laurs and Elizabeth P. Quinn
Gemological Institute of America
Carlsbad, California