INNOVATION Sept-Oct 2019

RARE BLUE GEM RECIPE UNEARTHED BY BC RESEARCHERS

Showings of sapphire, spinel and lapis lazuli on Baffin Island in Canada’s Arctic led a UBC geoscientist and a PhD student to identify the specific pressure, temperature, and chemical conditions required to form these rare and beautiful gems.

KYLIE WILLIAMS

A fter they are cut and polished, gemstones are primarily valued for their beauty in jewelry. In recent years, consumers have been incorporating a wider rainbow of coloured gems into jewellery because they cost less than diamonds, according to the Gemological Institute of America. In addition, news that the world’s largest source of pink diamonds— Australia’s Argyle diamond mine—is set to close in 2020 suggests that opportunities for alternative sources of coloured gems may one day intrude into the diamond market. High-quality, coloured gems develop under a range of geological conditions: some crystalize rapidly within plutonic rocks, others grow more slowly as water percolates though surface sediments, and yet others form during extreme deformation of rocks at high temperatures and pressures over millions of years. These processes intrigue gemmologists, who examine subtle clues that are baked into the rocks that host gems found near the surface today. Some say that the natural formation of large, clear, and colourful gemstones is almost like baking a perfect cake: the combination of temperature, timing, and a variety of essential ingredients must be just right. Researchers at UBC in Vancouver used a series of analytical techniques to determine the precise conditions that resulted in rare showings of sapphire, spinel, and lapis lazuli on Baffin Island in the territory of Nunavut in Canada’s remote Arctic. Why does one outcrop of rock host a bevy of beautiful blue gems, when an outcrop of similar rock only steps away is barren?

GEM DEPOSITS PIQUE RESEARCHERS’ INTEREST In 2001, Lee Groat, P.Geo., a mineralogist at UBC, heard that two Inuit brothers, Nowdluk and Seemeega Aqpik, had discovered sapphire, a variety of the aluminum oxide mineral corundum, in Nunavut, on Baffin Island. Groat’s interest in gemstone formation in northern Canada had been piqued a few years earlier when Groat and one of his students discovered green crystals in Yukon, which were later identified as emeralds when inspected more closely. “Gem deposits are rare because they represent unusual geological conditions,” said Groat. “We can learn a lot from studying gem deposits. Canada’s non-diamond gemstone deposits have not really been studied in any detail.” Baffin Island, located in the Qikiqtaaluk Region of Nunavut, is the largest island in Canada at over 500,000 square kilometres. The southern part of Baffin Island has large expanses of marble— limestone that has been exposed to heat and pressure over millions of years. Marble is a metamorphic rock composed mostly of calcite, a calcium carbonate mineral, but impurities in this particular limestone, such as lenses of finer mud material, coarser sand, or salty evaporites, can play a key role in gemstone formation. Areas on Baffin Island have long been used by Indigenous people as a source of carving rock used by Inuit stone carvers and artists in sculpture. Several large mining projects operate on Baffin Island, harvesting various types of minerals. On northern Baffin Island,

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