A NEW OUTLOOK FOR THE PEND OREILLE CARBONATE-HOSTED ZN-PB DEPOSIT, WASHINGTON STATE

The Pend Oreille zinc-lead deposit in NE Washington is composed of several mineralized horizons, which have historically produced 14.8 Mt of ore grading 2.3% Zn and 1.1% Pb. Most historic production has come from the Josephine Breccia, a partially silicifed dissolution-collapse breccia located near the top of the Metaline Formation. Located 330 and 580 meters below the Josephine Breccia, Yellowhead-type mineralization is composed of several massive, stratabound, fine-grained pyrite-marcasite, sphalerite, and galena horizons. The best-known mineralized horizon, Yellowhead-I, is slightly offset to the west, with respect to the thickest part of the Josephine Breccia. Trending to the NNE, the Yellowhead-I Horizon measures 2400 m long, 300 m wide, and up to 20 m thick. Metal zonation consists of a central (100-200 m wide) pyrite-sphalerite-galena body that grades outward into 600-700 m wide pyritic sheet. Sulfides commonly display colloform, botryoidal, and crustiform textures intergrown with by a late stage, dolomite cement. Macroscopically, the Yellowhead-I Horizon consists of three textures (nodular sulfide, massive sulfide, and mineralized breccias) that appear to represent original host rock textures. Nodular sulfides appear to have replaced zebra dolomites, while massive sulfides occur at the intersection of structures and completely replace the host rock. Mineralized breccias occur in areas where previous dolomitic breccias have been replaced. The Pend Oreille mine is projected to have a 10 year mine life based on probable reserves of 5.5 Mt grading 7.3% Zn and 1.3% Pb after dilution, and inferred resources of 0.6 million Mt grading 5.6% Zn and 0.9% Pb and 2.0 Mt grading 6.5% Zn and 1.9% Pb.