Growing up in Cobalt, Ontario, I heard the stories about the 800-carat Nipissing Diamond found in the 1900’s but being that it is the Silver Capital of Canada, the story was often overshadowed. However, in recent years there has been a flurry of activity in the area and the local community is buzzing because an unnamed company (DeBeers) has been flying over the area from as far north as Kirkland Lake to as far south as Temagami. On a recent trip to Cobalt, we actually got to see the Helicopters using SKYTEM, and in talking to some of the locals, we found that they were actively speaking to property owners in the area, fishing around for information. Naturally, we wanted to understand what had caused the sudden influx in interest in the surrounding area and we got to work on our own investigation.
We were unable to get any answers form DeBeers and so we went through RJK Explorations, (a local company) to gain access to Tony Bishop, a local prospector searching for diamonds. Tony Bishop and his family have been working on the Bishop claims for a number of years sampling and researching in great detail. In 2019, Tony signed an agreement with RJK Explorations for the exploration rights to drill some of the suspected kimberlite pipes on the Cobalt claims, in hopes of finding the source of the famed Nipissing diamond. RJK was very accommodating and gave us a direct line to Tony so that we could better understand why the area had become a sudden hotbed of exploration activity.
Doug Robinson, an experienced local geologist (P.Eng) and good friend of the Bishop family, worked in the Cobalt area for the Timiskaming Silver Mine for many years. Like Tony, he is an avid rock and mineral collector with a passion for prospecting in the area. He became a valued asset too this project as he often assisted with the identification of odd minerals and helped sort out details associated with Tony’s ideas on new methods for advanced diamondiferous kimberlite exploration techniques. In order to attract attention to his own gold properties, he asked for permission to include Tony’s diamond projects, pictures and notes on his website. This was a useful arrangement for both as Doug received some attention on his property from several companies, and more importantly the website brought attention of the Bishop’s quest for the Nipissing Diamond to Glenn Kasner and RJK Explorations Ltd., and the rest is history in the making.
I’m going to give you a synopsis of some of their findings and I’m sure you will be as intrigued as my colleague and I, after reading through all the documentation and having a chance to sit down with Tony and his family.
Discovering a passion for Diamonds
Almost 40 years ago Tony and Shelley Bishop first took an interest in the area and would often come up to Cobalt metal detecting in search of silver and from time to time go exploring for gold. They actively searched for gold and silver in three provinces – Ontario, British Columbia, and Nova Scotia which led to a book written by Tony, ‘The Gold Hunter’s Guide to Nova Scotia’. As time went on, their hobby turned into a passion and became a way of life for them. Thirty years ago they met two men named Keith Barron and Rob Towner, who sought Tony out for his expertise in the effects of glaciation on placer mining in Canada. Rob had sapphire and gold properties Montana, and Keith was looking for kimberlite and the source of the Nipissing Diamond.Tony, having some knowledge of kimberlites, took an interest in what they were doing and began doing some research of his own.
Many years later in 2014, while exploring Google Earth, Tony was looking in and around the historic Cobalt and Silver Centre mining camps. This was a turning point for Tony as he identified a number of oddly placed round ponds situated just southeast of Cobalt. This inspired his search for the source of the Nipissing Diamond. He began staking claims and formulating a thesis about the source of the diamond that would see him prospect in great detail for the next 4 years as he aimed to prove out his theory.
Tony was aware of the Kimberlite pipes in the area that ran along the Temiskaming fault system and quickly came to realize that his newly staked claims were in fact part of the same system. With the encouraging results from his first claim at Paradis Pond, Tony felt that he may be onto something much bigger and went to work. He researched relentlessly to gain a better understanding of the history of the area and to learn as much as he could about kimberlite indicator minerals (KIMs) so that by the time the snow cleared he would be ready to start a sampling program.With a background in placer mining and concentrating fine gold, Tony was perfectly suited to take on this kind of project and did so with great enthusiasm.
Here are some key points about the formation of diamonds and the nature of diamond exploration in Canada which are pertinent to this story.
How diamonds are formed
Diamonds: Approximately 150 km below the earth’s surface at the Mantle, where temperatures reach above 1093.3 degrees Celsius and pressures that exceeds 725,000 pounds per square inch is where diamonds are formed. The extreme heat and pressure have enough force to alter carbon in the form of graphite locked in Cratons (ancient part of the Earth’s continental crust) from their hexagonal sheet patterns into a triangular shape resulting in the formation of diamonds. This is important because without the exact temperature, heat, pressure and carbon… Diamonds cannot form…
Method of Transportation
Kimberlite pipes: Kimberlite pipes are Ultramafic rock which is composed of fragments of peridotite and basalt/eclogite with a high potassium, water and carbon dioxide content, derived from the upper mantle. As magma pushes through the Mantle and erupts in a violent explosion, it forms what’s known as a Kimberlite pipe. This is important to know because it is part of the transportation method for diamonds to reach the surface. As they cool the diamonds become encased within the ultramafic rock of the Kimberlite pipe.
Faults: The Temiskaming region is situated on a series of faults which run North/South and formed as supercontinents shifted and melded together during the Jurassic period approximately 155 million years ago. These faults created shears during earthquakes which presented the opportunity for kimberlites to form. Maybe one of the more interesting aspects of this fault system is that they overlap a large Craton and are part of a much larger trend which extends into Northern Canada. Basicallythere is a recipe for success of diamond formation opportunities.
Distribution of indicator minerals
Glaciation: Large continental ice sheets covered most of Canada at one time, or many times for that matter which have had profound effects on shaping the landscape. These glaciers are responsible for moving rocks and mineral as they advanced and receded through the peaks and valleys. We know the way the ice advanced and retreated due to features left behind on bedrock by the glaciers. This is also important in determining where the source of diamonds originated particularly in Canada as they play a significant role in distributing indicator minerals unlike in Africa where glaciation does not play a role.
Elevations: The changes in elevations tie into glaciation. The glaciers will follow the valleys in the mountains and deposit the indicator minerals along these trends but even small hills and valleys have an effect on the way indicators are deposited. This becomes important as you attempt to retrace where the source of diamonds ultimately came from. This also plays a role in the erosion of the indicator minerals as they are carried away from the source in that the further they are transported, the more they will erode.
Indicator minerals: Kimberlites are peculiar igneous rocks because they contain a variety of mineral species with chemical compositions that indicate they formed under high pressure and temperature within the mantle. These minerals; such as chromium diopside (a pyroxene), chromium spinels, magnesianilmenite, and pyrope garnets rich in chromium, are generally absent from most other igneous rocks, making them particularly useful as indicators for kimberlites.
Prospecting and analysis
After Tony staked his claims, the first thing he had to do was identify how glacial movements affected the distribution of indicator minerals. It was long believed that the Nipissing Diamond could have originated from previously identified Kimberlite pipes in the New Liskeard and Haileybury area, but Tony wasn’t prepared to accept this as fact and wanted learn more about how the glaciers affected the area.
Once the topography of the land and localized variations in glacial flow (based on observable striae and information in OGS and GSC reports) was understood, Tony and his family began sampling his claims down-ice of a number of potential kimberlite pipes and quickly discovered that the indicator minerals were more prevalent down-ice on each of his targets. Between 2016 and 2018, Tony submitted twelve technical reports on his legacy claims to MNDM, highlighting his findings and theories of deposition.
“The sample area is more than 15 km south of and ~ 30 to 60 metres higher in elevation than the known kimberlite pipes in the New Liskeard area, making it possible but unlikely that the KIMs are from any known pipe. These results, taken together, fairly conclusively point to a number of selected targets being the source of the high KIM counts in close proximity down-ice, especially when so many off-ice samples surrounding these lakes have low to no KIM counts.
Tony Bishop, 2017 Report
So while it’s not definitive, the picture began to take shape as to where to start looking for the source of the Nipissing diamond. Clearly there was more work to be done and so Tony and his family carried on working under their model that the indicator minerals originated close by and not carried over any kind of great distance. There was no evidence to suggest indicators were carried uphill 60m above the established kimberlites in New Liskeard and deposited beyond the great silver mines of the Cobalt silver camp. In the conclusion of a 2017 report on his Ice Chisel-Darwin Lakes claim for example, Tony goes on to say…
“Many kimberlitic grains were observed (in the dozens to many hundreds) in samples taken on the claims, especially immediately south of Ice Chisel Lake. Darwin Lake also returned above background results, but was harder to sample. My results were later checked by re-sampling near and in a similar fashion to be sent to ODM for processing. They too found way above background levels of KIMs.”
Typical Ilmenites, chromium diopsides, garnets and pyropes were found as expected but a number of unusual grains were also identified, such as clear yellow quartz, also called Citrine, which is quite a rare mineral in nature. Once you combine the glaciations patterns and the indicator mineral data you can start to trace these indicators back to their source.
Several intact garnets, some brecciated, have been found on the claims, which are in the 2-2.5mm range down-ice of a number of Tony’s targets which is very encouraging because most of the grains that diamond explorers find are much smaller (most diamond exploration companies only search for grains in the 0.25 to 0.5 mm range due to the scarcity of larger grains) until they get close to diamondiferous Kimberlite pipes. You see as indicators get shifted through the kimberlite and carried by glaciers, they tend to break down into many smaller grains. So generally, the larger the indicators, the closer you are to finding the source. Here is a chart that will help you understand how this works in more detail.
“2.5mm grain is the potential equivalent to 1000 0.25mm grains.”
With all this information it’s easy to see why Tony and his family have carried on for years on these claims. The geology fits the bill so to speak as the Temiskaming faults run right through this area and many shears extend off of these faults creating the perfect opportunity for Kimberlite pipes to form.
Kimberlite pipes often form in clusters as they tend to follow the associated fault systems. The evidence is starting to pile up through the use of historical documents, Tony’s prospecting efforts and intensive research which is why RJK Exploration in conjuction with the Bishop family have been aggressively staking claims. They now have one of the largest land packages within the Cobalt mining Camp ever to have been assembled and have identified up to 35 potential targets for exploration.
In conclusion, RJK Exploration and the Bishop family will be actively continuing their search for the source of the Nipissing Diamond in the coming months and i suspect we will hear about their plans in the very near future. I am as excited as anyone as to what this could mean for the future of Temiskaming Shores and the locals who have endured economic downturn with the closure of most of the historic silver mines of Cobalt. This story is just getting started and we are proud to be a part of it in a roundabout way.
For more information here are a few videos put together for RJK Exploration and Tony Bishop.
REFERENCES & RESEARCH
Structure of diamonds
Kimberlite/ craton animation
Diamonds in the rough: jewels beneath the Earth’s crust
Temiskaming Shores geological features
Kimberlitic indicator minerals
2017 technical report by Tony Bishop
Diamond Trends in Canada
Source for the Indicator Minerals photos:
McClenaghan, M.B. ,Kjarsgaard, B.A. (2001). Indicator mineral and geochemical methods for diamond exploration in glaciated terrain in Canada. In Drift Exploration in Glaciated Terrain. Geological Society of London, Special Publications, 185, 83-123
Caption: Examples of typical colours and surface features of kimberlite indicator minerals: (A) purple and mauve Cr-pyrope, some retaining kelyphite (dark); (B) emerald green Cr-diopside; (C) opaque black Cr-spinel, some exhibiting slightly resorbed octahedral form; (D) black Mg-ilmenite, both single crystals and polycrystalline morphologies shown; (E) yellow Mg-olivine; (F) orange eclogitic pyrope-almandine garnets. Photos A to E from the Geological Survey of Canada, photo F from Mineral Services Canada
Source for The Down Flow Diagram:
Cummings, D.I., Kjarsgaard, B.A., Russell, H.A.J., and Sharpe, D.R., (2014). Comminution of kimberlite indicator minerals in a tumbling mill: Implications for mineral exploration; Geological Survey of Canada, Open File 7111. doi:10.4095/293467 accessed at http://publications.gc.ca/collections/collection_2014/rncan-nrcan/M183-2-7111-eng.pdf
Caption: Farther downflow, total KIM counts would decrease, assuming continued comminution (in addition to selective sorting and/or dilution). (Cummings et al. (2014))
RJK Exploration is a sponsor of Insidexploration and we hold a position in the company. The contents of this article are not meant as investment advice and readers are advised to seek a financial advisor prior to making investment decisions.