On a recent trip to Brazil, I was fortunate to have an opportunity to travel through the eastern state of Minas Gerais visiting various gem mines with a friend who is a well-known Brazilian mining geologist. Minas Gerais or “General Mines” is the largest gemstone mining region in Brazil. It is about the size of California and Florida combined and is a major source of fine aquamarine, tourmaline, topaz, emerald and numerous other gems. The region is experiencing renewed activity due to the tremendous increase in global demand for colored gemstones.
Map of Minas Gerais courtesy of Brazil Travel, www.v-brazil.com
Continued strong demand from the U.S. and EU for aquamarine and emerald and the dramatic increase in demand from China for tourmaline has resulted in less supply and thus higher prices. Environmental concerns brought about new environmental mining laws that forced many Brazilian mines to close until they could afford to adhere to higher environmental standards. Many mines had either halted mining efforts or were on the verge of shutting down when the Chinese market resurrected demand for all colored gemstones. This resurgence may also be partly attributed to increased domestic demand, particularly for Imperial topaz and emerald fueled largely by the success of Brazilian designers and retailers.
Besides enjoying the fabulous beaches, I focused my time in Rio de Janeiro visiting the gem and mineral museums at Amsterdam Sauer and H. Stern. Their extensive collections of mineral specimens and gems combined with exhibits about the history of mining in Brazil are well worth the visit.
Later I flew to Belo Horizonte, the capital of Minas Gerais to see the many gem dealers in “Belo” as the locals call it. There are numerous buying offices throughout the city, which makes it easy to compare gems and pricing. I chose to stay in an old 1950s business hotel located next to an elegant 19th century Gothic cathedral. Every morning, to my pleasant surprise, I would awake to the morning bells of the Igreja de boa Viagem, “Church of the Good Journey," which made me feel even more confident of my upcoming trek to the mines.
After several days in Belo, I endured a 12-hour bus ride to Governador Valadares to connect with my geologist friend and tour guide to the tourmaline mines nearby.
Our first stop was a commercial mine where gems were recovered from within a huge granitic pegmatite as a bi-product of feldspar and lepidolite mining. Feldspar is used as a fluxing agent in ceramic and glass manufacturing and lepidolite for lithium used in lubricants and cell phones. Amazingly, this pegmatite was so large that we could drive our truck right into it. Pegmatites are igneous intrusives that penetrate pre-existing country rock and sometimes form gem crystals within pockets or small voids as the pegmatite cools.
Huge pegmatite near Governador Valadares
In a typical gem-bearing pocket, black tourmaline forms initially on the periphery while the gem-quality red, pink, and green tourmalines crystallize last toward the center of the pocket.
Empty gem pocket in the above mine with remaining black tourmaline
Huge quartz crystal cluster with large box-like feldspar crystal (bottom right)
The next few days were spent driving north to the little mining village of Cruzeiroor “Cross,” which is also the name of a famous tourmaline mine nearby. A prominent golden yellow cross in front of a church above the village gives away the origin of the name. We also came across a couple of miners riding a horse and another on a donkey while talking on his mobile phone. Unfortunately, I couldn’t capture that image but did manage to get a shot of their transportation parked outside a local bar. I see this leapfrogging of traditional landlines in almost all remote gem-producing countries. Such access to technology allows even the miners to communicate with potential buyers, thus contributing to higher prices even at the source.
The village of Cruzeiro “Cross” and local transportation
The Cruzeiro tourmaline mine had been closed for several years before my visit due to the high cost of mining. Only a few weeks before, they were able to re-open the mine thanks to Chinese demand for tourmaline, which now made it economically feasible to mine again. Though the miners had still not hit any gem material while I was there, a few months later they reported uncovering a fine pocket of rubellite.
The author (far right) with miners from the Cruzeiro tourmaline mine
Bluish green tourmaline (22 carats) with a typical Portuguese-style cut
Photo by R. Weldon
The next mine we visited was the Pedeneira tourmaline mine, which is famous for its long, slender pencil-like green tourmaline crystals. The several-hour drive, which took us through a thick forest of ferns, felt like being on another planet. This mine is unusual because the facet value of its crystals is less than its mineral specimens, which are highly sought after by collectors and museums alike. Most of the specimens must be repaired to their original state because they have either broken inside the pocket over millennia of tectonic activity or from blasting. Un-repaired specimens are extremely rare.
Miner pushing an ore cart out of the Pedeneira mine to the sorting area.
A local dealer offering green tourmaline crystals for sale in OuroPreto