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| Figure 1. Demantoid garnets from Iran have been mined in shallow workings such as this tunnel, which Makhmout Douman visited in November 2003. Although this tunnel proved uneconomic, other workings on nearby hills have yielded significant quantities of the garnets. Photo by R. Sadeghi. |
During the Tucson show, one of these contributors (MD) showed GIA personnel two cabochons of cat’s-eye demantoid from Kerman Province, southern Iran. Based on the experience of this contributor, who regularly visited the deposit from early 2001 to November 2003, this report provides an update on the mining and production of the demantoid from this area, as well as the appearance of the chatoyant material. The gemological properties and color range of this Iranian demantoid were described in the Spring 2002 Gem News International section (p. 96).
The site is located at 28°19’N and 57°45’E, between the villages of Bagha Borch and Soghan, which lie approximately 150 km south of the town of Jiroft. Travel from Tehran to Jiroft takes about 16 hours, although considerable delays may be encountered along the highway, which is heavily patrolled to prevent drug smuggling. The journey onward from Jiroft to the site requires three hours of driving on a rough road.
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| Figure 2. Some of the Iranian demantoids are chatoyant, such as the 7.06 and 5.00 ct examples shown here. The 41.73 ct composite crystal also contains the chatoyancy-causing fibers. Photo © GIA and Jeff Scovil. |
The mining area (figure 1) is situated approximately 1,500 m above sea level, and consists of several tunnels and small pits scattered across an area of approximately 500 m2. Mining is done by hand, mostly in December–March when the weather is cooler. The workings range from 2 to 8 m deep, and about 10 miners are active during the cool season.
The demantoid crystals are hosted by regionally metamorphosed asbestiform rocks. The garnets range from yellowish green to dark “emerald” green, and faceted stones are known up to 7 ct, although they typically weigh about 0.7 ct. Round nodules up to three grams, mostly in dark green and orangy yellow, have also been found, as well as large, well-crystallized translucent specimens on the order of 5 cm in diameter. Approximately 20 kg of rough was extracted during the 2003–2004 season. Of this, 1.5 kg was facet-quality, with about 200 grams yielding stones of more than 2 ct in good color and clarity.
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| Figure 3. Parallel to semi-parallel fibers (possibly chrysotile or byssolite), together with associated oriented micro-cracks, are responsible for the chatoyancy seen in some of the demantoid garnets from Iran. Photomicrograph by John I. Koivula; magnified 20¥. |
Chatoyant demantoid from this area was first encountered by one of these contributors (MD) in November 2003. Approximately 35 grams of crystals and crystal fragments were collected, some of which were polished into cabochons of 5–10 ct (figure 2). A few chatoyant demantoid crystals also were noted, such as the 41.73 ct specimen in figure 2. The chatoyancy is caused mainly by concentrations of parallel fibers (figure 3) that are, based on their appearance, possibly chrysotile or byssolite.
Makhmout Douman (makhmout@arzawa.com)
Arzawa Mineralogical Inc., New York
Dona Dirlam
Liddicoat Gemological Library, GIA, Carlsbad
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