Gem exploration may become cheaper and easier thanks to work taking place in Memorial’s Faculty of Science.
Researchers in the faculty’s Department of Earth Sciences developed a new method of analyzing fine-grained sediment.
Assistant professor Dr. Philippe Belley says the current approach of exploring for sapphire and ruby deposits involves taking large sediment samples to look for gems of potential economic value, which limits exploration to a more local scale.
“We’ve established a method that can be used to make meaningful comparisons between corundum — the mineral called sapphire or ruby when of gem-quality — found in sediments around the world, which will lead to a better of understanding of gem deposits,” he said.
Easier to detect
A recent paper published in the Canadian Journal of Mineralogy and Petrology reveals that in one sapphire deposit in Montana, corundum is far more abundant at small grain sizes (the size of a grain of sand) than in coarser grains of potential economic interest.
These abundant small grains would be easier to detect in general heavy mineral surveys and could be used to understand the distribution of corundum over large areas.
Dr. Belley says most coloured gemstone deposits are found by chance.
His lab is developing methods that can be applied on a regional scale, particularly in areas that are not historically known to produce gemstones.
Due to the high cost and risk, exploration capabilities are currently limited to a more local scale and are usually employed in regions with known deposits, he says.
“Our goal is to develop tools that will be incorporated into existing surveying efforts, for example, by federal and provincial geological surveys, which add little cost and could lead to discoveries of new gem-producing regions in Canada and abroad.”
However, Dr. Belley says there is more work to do in order to develop functional exploration tools explorers could use to hunt down ruby and sapphire deposits, but his lab is advancing towards this goal.
Identifying source rocks
Ofure Onodenalore, Dr. Belley’s graduate student, is currently studying the trace element and oxygen isotope composition of tiny corundum grains found in surface sediments from sites across Canada in order to identify potential source rocks.
Dr. Belley says the grains give the researchers a first glimpse into corundum-bearing environments in parts of Canada that have never been examined for ruby and sapphire deposits. Dr. Belley also says they also indicate whether or not the physical properties of the corundum grains exclude gem potential.
“While the method has limitations, it is one of the most efficient approaches for detecting the presence of corundum at regional scale,” he said.
The grains were provided by the Geological Survey of Canada, prospectors, and provincial and territorial surveys.
Rubies in Labrador?
Additionally, undergraduate honours student Emma Mercer is comparing pink corundum found in a coastal rock exposure near Hopedale, Labrador — an occurrence discovered by Indigenous prospector Edmund Saunders — to grains found in surface sediments more than 27 kilometres away by Heather Campbell, a Newfoundland and Labrador Geological Survey geologist.
“These occurrences suggest that potential ruby-forming environments are widespread in the Hopedale area, but there are as of yet no clear indications for the presence of larger, gem-quality ruby corundum,” said Dr. Belley.