In late August 2009, these contributors visited a relatively new tsavorite deposit, located 110 km south of Arusha near Namalulu Village. Tsavorite was reportedly discovered there in August 2008 by Masai herders. Mining activities peaked in December 2008 when approximately 500 people worked the deposit, but this number soon decreased as the near-surface deposits were exhausted and underground hard-rock mining became necessary. In addition, at the end of 2008 most of the miners moved to the former Swala Gem Traders tsavorite mine at Lemshuku, near Komolo Village, also in northern Tanzania.
Upon our arrival at Namalulu we were met by several members of the Masai tribe, who were dealers as well as miners there. We estimated that about 150 people were active in tsavorite mining or trading during our visit. The workings were confined to a narrow band approximately 100 m wide and 1 km long, oriented in the north-south direction. The tsavorite is hosted by veins associated with folded graphitic gneisses near dolomitic marbles.
Most of the mining has taken place during the dry season, from May to November. The largest mine we visited consisted of a shaft and horizontal tunnels with an estimated total length of 250 m. The shafts were accessible by ropes and followed the near-vertical graphitic gneiss layers downward. The excavations were mainly done using hand tools and explosives, except for one shaft where a compressor and a jackhammer were present.
The miners reported finding good tsavorite every two days, on average, and we saw many attractive parcels while visiting the area. Most of the rough was vividly colored in yellowish green to deep green, with some bluish green. We were told that pieces larger than 2 g had been recovered, but we only saw 0.6-0.8 g pieces that had fine color and acceptable clarity.
Vincent Pardieu, GIA Laboratory, Bangkok
Stephane Jacquat, Geneva, Switzerland
Lou Pierre Bryl, Gaspé, Canada
courtesy of Gems & Gemology eBrief