Gem News International Gems & Gemology, Volume 46, No. 1

Update on Ametrine from the Yuruty Mine, Bolivia

This ametrine (6.46–35.59 ct) was recently mined from the Yuruty deposit in Bolivia. Photo by Robert Weldon.
During the Tucson gem shows, Hugo Marancenbau (Steinmar Ltd., Santa Cruz, Bolivia) provided an update on ametrine from the Yuruty mine in Bolivia (see Summer 2000 Gem News, p. 163). This deposit was initially claimed in the mid-1990s and is located ~50 km north of the famous Anahí ametrine mine. Mining at Yuruty has been intermittent, although commercial production was resumed during the past two years. The deposit is exploited by ~100 people in underground workings consisting of a 90 m shaft and four horizontal tunnels up to 200 m long. The mine produces an average of ~40 tonnes/month of mixed-grade material, approximately 3% of which is facetable. Although Mr. Marancenbau’s company plans to sell the ametrine in the rough form only, they have test faceted a few thousand carats (weighing 3–30 ct each) that were sold at the JOGS show. He indicated that it was the first time ametrine from this mine was sold in Tucson.

Mr. Marancenbau kindly donated several rough and cut pieces of ametrine to the GIA Collection. The faceted stones (figure 2) contained varying amounts of purple and yellow, with a sharp color boundary visible face-up in one of the samples. None of them had the distinctive smoky layers seen previously in Yuruty material (see the Summer 2000 Gem News entry).

With several tonnes of rough material stockpiled and good reserves that are inferred to remain underground, the Yuruty deposit appears poised to become an important supplier of ametrine.