In October 2011, I took a short trip to Sweden, invited by Tasman Metals Ltd. (TSX.V:TSM, AMEX:TAS, F:T61) to join an analysts’ tour of Norra Kärr, Tasman’s flagship rare-earth-element (REE) project in Scandinavia.
First things first: the Swedes spell the name of this mineral occurrence as ‘Norra Kärr’, not ‘Norra Karr’. This spelling renders the project’s pronunciation as something similar to “Nora Shah”, instead of “Nora Car”. The things you learn on the way to learning other things…
Norra Kärr is located 10 miles northeast of the town of Gränna, which itself sits on the shores of the beautiful Lake Vättern, Sweden’s second largest lake and found in the south central part of the country. The city of Jönköping and its 90,000 inhabitants are 30 miles to the southwest; Stockholm is around 200 miles away to the northeast. Norra Kärr is readily accessible from all parts of the country via the E4 highway that runs close to the deposit. And by close, I really do mean close; while standing in the middle of the deposit, we could hear the cars whizzing by on the highway. Clearly then, accessibility is a key positive for this mineral deposit, regardless of what might be present in the ground. Power and water are also available right at the site.
Having flown into Stockholm the night before, early the next morning the group piled into a couple of vans and cars, for the 3.5 hour drive to the project from the Swedish capital. I spent the journey in the company of Tasman’s Chief Geologist Magnus Leijd, and Yasushi Watanabe, the well-known senior geologist with the Geological Survey of Japan, and who was also along for the visit. This was an excellent opportunity to listen to the two geologists talk about the project, and for me to pose a bunch of layman questions, which fortunately they were both only too happy to answer.
Along with Mr. Leijd, our Tasman hosts included Mark Saxon, President & CEO, Jim Powell, VP for Business Development and Henning Holmström, Project Development Manager.
Norra Kärr is the only rare-earth project in mainland Europe with an NI-43-101-compliant mineral-resource estimate. Per the most recent numbers at the time of writing, Norra Kärr contains an estimated 60.5 Mt of rare-earth mineral resources, at an average grade of 0.54%, resulting in an estimated 327 kt of rare-earth oxides (REOs) present. In addition to the production of rare earths, the project is of interest for zirconium (Zr), hafnium (Hf) and possibly niobium (Nb) as well. Oxides of europium (Eu) through to yttrium (Y) make up 53% of the total REOs (TREOs) present, thus Norra Kärr has one of the most attractive TREO distributions of any rare-earth project with a defined resource. Despite the relatively low overall TREO grade in the deposit, the actual in-situ grades of dysprosium (Dy) and Y, two of the critical REOs (CREOs), are some of the highest of any defined resource.
All of these factors, combined with very low concentrations of thorium (Th) and uranium (U) (7 ppm and 14 ppm respectively), mean that the deposit is of high potential strategic interest.
You can see photographs taken during the visit, in galleries on the Technology Metals Research web site.
Mr. Leijd indicated that the main minerals of interest at Norra Kärr are eudialyte (85%) and catapleiite (10%), and other minerals that closely resemble them. The latter is a Zr silicate not unlike eudialyte. Norra Kärr probably has the largest occurrence of catapleiite currently known in the world. As an aside, he made the interesting comment that the more intense the characteristic pink color is in a eudialyte sample, the less rare earths it contains, with the mid-brown eudialyte being preferred. The host rock consists of feldspar, nepheline and pyroxene.
There are few exposed outcrops at Norra Kärr; much of the surface is covered by so-called glacial till. Mr. Leijd mentioned that since much of Sweden has been covered in ice in the recent geological past (10,000 years, which is recent to a geologist), there are very few weathered rocks in the country. While this doesn’t sound all that important, its significance was pointed out to me. The lack of weathering means that the rare-earth minerals are the same at surface as they are at depth in the Norra Kärr intrusion, and they haven’t been altered to new minerals by the effects of air, water and time. While Norra Kärr is not unique in this regard, this lack of mineral variation should simplify subsequent processing of the deposit.
During initial bench-scale metallurgical testing, the main rare-earth-containing minerals were all very soluble in sulphuric acid, with the catapleiite dissolving faster than the eudialyte. Early in the company’s research, preliminary leach tests gave only a 50% rare-earth element (REE) yield. However, after analyzing the residues and mass balance of the metals, the folks at Tasman noticed that most of the remaining mineral was eudialyte, and were able to refine their processing to recover up to 90% REEs in solution. Since my site visit, Tasman has released the next round of metallurgical results, arising from their work at the laboratory of the Geological Survey of Finland. They appear to have made good progress, with a mineral-concentrate step and room-temperature leaching both giving good recoveries.