A new jewel in the crown
Geologists locate tourmaline deposit in NWT
by Anne-Marie Jennings
NNSL (Apr 06/98) - A group of researchers has discovered a new deposit of a semi-precious gemstone in the western Deh Cho.
Initial signs of tourmaline were uncovered close to the headwaters of the Nahanni River. Scott Ercit, a geologist with the Canadian Museum of Nature and co-leader on the tourmaline project, said the deposit uncovered by his team suggests there is still more to be found.
"There is quite a bit of tourmaline," Ercit said. "What we found in our mapping was all on the surface."
Pegmatite is the rock in which tourmaline is found. It is rock which Ercit said many people have probably seen, but were not able to recognize for its potential economic value.
"Pegmatite is nothing special to look at," he explained. "It looks a lot like granite, except the crystals in the rock are bigger."
The joint project with the University of British Columbia was looking for specific rock types known to occur in B.C., the Yukon, and the territories and similar to ones found along the Rocky Mountains.
"With a little bit of knowledge and a lot of reading, we were able to select a series of targets," Ercit said. "This area was on our short list."
The group first found evidence of pegmatites in 1994, but was not able to return to investigate more closely until last summer.
Lee Groat, an associate professor in the Department of Earth and Ocean Sciences at UBC and co-leader on the project, said the genesis for the project came from a memoir published by the Geological Survey of Canada.
"The memoir said that they had seen pegmatite in this area, but hadn't said very much," Groat explained. "We feel they were working on a large-scale mapping project and didn't spend much time there."
Ercit added that the discovery of the pegmatite did not require any special equipment -- just a good pair of eyes.
"We had been walking over tourmaline, but it was black," he explained. "Then a graduate student looked down and found a piece that was blue."
While not a popular gemstone on the scale of diamonds or emeralds, tourmaline is used in necklaces and earrings. Ercit said that the majority of tourmaline jewelry is bought in California and China.
Tourmaline has also been used in the construction of pressure gauges because of its ability to conduct electricity when pressure is applied.
Ercit said that while the NWT is not known as a source of tourmaline, this new discovery could change that perception.
"It's gemmy and the color is just right," he said. "The main interest is as a gemstone -- if it's found," he said. "The future of tourmaline is very much in the marketing."
Groat said that the group hopes to return to the North in the future to examine new areas, but he added the next trip will probably not happen until the summer of 1999.
"We're writing up a scientific documentation report," he said. "We have a lot of information to write up.
"It's beautiful country. We're running out of scientific reasons to return."