Resource World Magazine

46 www.resourceworld.com A U G U S T / S E P T E M B E R 2 0 1 4 Duluth Metals Ltd. [DM-TSX] is excited about its upcoming release of a Pre- Feasibility Study for its Twin Metals Minnesota LLC [TMM] copper-nickel-PGE- precious metal project in northeastern Minnesota, US. One of three large Cu-Ni- PGE exploration projects in development along the basal contact of the Duluth Complex, along with Teck's Mesaba (Babbitt) deposit and PolyMet Mining's NorthMet deposit, the TMM is a joint ven- ture between Duluth Metals (60%) and Antofagasta plc (40%) [ANTO-LSE], a Chilean copper mining company. Resource World reported (in 2010) on exploration work of Franconia Minerals Corp. in this area; Franconia was subsumed into Twin Metals Minnesota LLC in 2011, thus com- bining two adjacent but separately explored targets, Nokomis and Maturi, into one large deposit now known as the Maturi. For more than a century, northeastern Minnesota has been mined for iron ore, and the Duluth Complex has long been known to be prospective for copper and nickel sulfides, platinum group elements, and precious metals. In the late 1970s, the state of Minnesota halted explora- tion for copper and nickel sulfides to study regional resources as a whole, and to establish best-use guidelines for vari- ous areas. Along the border of Minnesota with Ontario, regulations regarding the Boundary Waters Canoe Area Wilderness were defined. For a while, not much mining development occurred due to com- modity prices and metallurgical difficulties with ore extraction. In recent years, however, the Minnesota Minerals Coordinating Committee (state government) has encouraged mineral exploration, as the state has a long history of mining, was a favourable jurisdiction and had excellent infrastructure and avail- ability of knowledgeable workers, as well as potential copper-nickel PGE prospects. Currently in Minnesota, eight operat- ing taconite mines (iron ore) are located along the east-northeast trending Biwabik Iron Formation in contact with Archean granite, near the town of Babbitt. Here the crosscutting basal contact of the 1.1 billion year old Duluth Complex trends northeast, and hosts several Cu-Ni-PGE sulfide deposits in cumulate layers of anorthosite, troctolite, gabbro, and melatroctolite, overlying older iron-bearing units. The four main deposits of Twin Metals Minnesota – Birch Lake, Maturi (includ- ing former Nokomis), Maturi Southwest, and Spruce Road areas – as well as Teck's Mesaba and PolyMet's NorthMet, are located along this contact zone, known as the BMZ (Basal Mineralized Zone) of the SKI (South Kawashiwi Intrusion). TMM's comprehensive package of federal, state, and private mineral leases add up to some 10,000 hectares of exploration and poten- tial mining land; details can be found within past and updated technical reports. Summarizing data from all four TMM qualified resources, the combined resource base reported in April 2014 is, with a cut- off grade of 0.3% Cu: measured resources of 295 million tons with 0.63% Cu, 0.20% Ni, 0.148 ppm Pt, 0.345 ppm Pd, and 0.084 ppm Au; indicated resources of 977 mil- lion tons with 0.56% Cu, 0.18% Ni, 0. 159 ppm Pt, 0.357 ppm Pd, and 0.084 ppm Au; and inferred resources of 1313 million tons with 0.47% Cu and 0.16% Ni. This size of copper-equivalent deposit shows up on a graph of Tier 1 assets in roughly the same category as Galore Creek, Oyu Tolgoi, Penasquito, Bingham Canyon, Red Chris, or Taca Taca, among others. Mineralization occurs in disseminated sulfide minerals, including 11 copper sul- fides (mainly chalcopyrite and pyrrhotite), five nickel sulfides (mainly pentlandite), two copper oxides, and native copper; a dozen precious metal minerals containing Au, Ag, Pt, and Pd, as well as some with Bi, Sb, Sn, and Pb; and various associated metal-bearing minerals such as tellurides, galena, sphalerite, chromite, ilmenite, and magnetite. Metallurgical studies have emphasized promising recovery of copper and nickel concentrates. Changes at Duluth Metals include new president and CEO, Kelly Osborne, with more than 30 years of world-class min- ing expertise including with Freeport McMoRan at Grasberg in Indonesia, Vulcan Materials, and Stillwater Mining. During a recent interview, Osborne spoke of what makes a great mine. First of all, a great ore body with good information (take a look at the upcoming pre-feasibility study, three years in the making). Second is using the latest mineral extraction equipment, effi- cient and highly skilled employees, and automated technology. They are looking forward to using amazing new technology for automating many mining processes, such as ventilation and dewatering, mak- ing underground mining ultrasafe. The company has been pro-active in going above regulations, planning underground operations with sensitivity to the local environment, wild rice ecology, wilderness areas, and communities. Osborne said, "We have a chance to build a great mine here. The project team will deliver a truly 21st century mine." n Duluth Metals' Minnesota project looking good by Jennifer Getsinger, PhD, PGeo MINING

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