Golden footprint - Earth sciences graduate student mapping ore deposits in real time
A Memorial graduate student is helping gold prospectors in Central Newfoundland zero in on new deposits — and fast.
Sam Ybarra, a master’s student in the Department of Earth Sciences, Faculty of Science, who hails from Columbus, Mississippi, is using infrared spectroscopy to collect mineralogical and geochemical data in real time.
Working with his supervisor, Dr. Steve Piercey, Mr. Ybarra has been mapping fluid rock, ore-forming footprints in Baie Verte, N.L., in partnership with Anaconda Mining.
Orogenic gold is formed when rocks along faults in the earth’s crust fracture and release water. As the fluid escapes, it scavenges gold from the rocks it passes and, when a favourable location is found, the gold is deposited.
The fizzy, carbon dioxide- and gold-bearing hot water also reacts with the rocks themselves, forming new minerals — a process called hydrothermal alteration.
Fast and efficient
The purpose behind Mr. Ybarra’s research is to map these fluid pathways, and the distinctive mineralogical and chemical changes in rocks surrounding the Pine Cove gold deposit in Baie Verte, to help determine how close or far away the ore may be.
Testing for those specific minerals using spectroscopy can quickly create an overall footprint of an area. Mr. Ybarra says it’s an effective way of mapping something you might not be able to see with your naked eye or with a hand lens.
“It’s fast and efficient, and you get consistent results,” he said.
“Usually, if you want to conclusively identify a certain mineral that is too fine grained to see, you would have to take a sample and make a thin section of it or send it off for geochemical analysis, both of which could have a turnaround time of weeks. This is something you can do without destroying the sample and have the results on the same day.”
Integrating field and lab
The technology has been available for some time; however, it isn’t always routinely used in mineral exploration. Mr. Ybarra says that while companies have a standard set of tools they normally rely on, many are starting to see the effectiveness of spectroscopy.
Only a handful of spectral studies have been done on fault-related gold systems globally, and few have integrated fieldwork through to the laboratory the way Mr. Ybarra has, according to Dr. Piercey.
“If the people who funded round one are going to fund round two, that shows there’s an intrinsic practical value.”
He says “one of the beauties” of the study is that it will operate as a template for others in the world who do the same kind of work.
“Sam has targeted these samples in the field using spectroscopy and then tested his results in the lab to make sure they were correct,” said Dr. Piercey.
“Then he integrated that data with the chemistry of the rocks. Most of what we’ve collected previously was empirical data that didn’t have the same level of rigour of Sam’s work.”
The data generated by Mr. Ybarra for Anaconda Mining led to so many advances for the company they are prepared to fund another suite of work on their other deposits. Dr. Piercey says this is a measure of the value of the work.
“Scientifically, there’s a big picture value outside of the gold community for understanding ore forming processes, but from a pragmatic perspective, if the people who funded round one are going to fund round two, that shows there’s an intrinsic practical value as well.”
Mr. Ybarra’s research and contacts have also led to new work for the laboratory. Recently, the researchers have begun analyzing samples from a company in Arizona that is generating revenue.
“What we can provide is unique expertise in the integration of spectroscopy with lab-based mineralogical and geochemical methods, such as x-ray diffraction, scanning electron microscopy and electron probe microanalysis,” Dr. Piercey said.
“They are coming to our lab in large part because of the expertise we’ve developed here and the suite of tools we have that can complement the portable infrared spectrometer, including those in Memorial’s Core Research Equipment and Instrument Training Network.”