Resource World Magazine

SEDIMENTARY EXHALATIVE DEPOSITS (SEDEX) CARBONATE-HOSTED DEPOSIT (Mississippi Valley Type-MVT) Medium to large tonnage, moderate to high grade Significance: The world's largest source of zinc, and a major source of lead Examples: Sullivan, BC; Faro, Yukon; Broken Hill, Australia. Hosted: Fine-grained sedimentary rocks such as shale, sandstone and chert within a large succession of sedimentary rocks (basin) Mineralization: Massive sulphide polymetallic lens hosting ore minerals containing Zn-Pb±Ag Structures and shape: Sheet like, lens or tabular shape. Mining method: Surficial and underground methods depending on the dip of the structure Drill intersection: Metres to tens of metres in length with combined Zn+ Pb grades in the 7-10% range, high-grade will exceed 15% Tonnes (Mt):20.0-50.0. Smaller deposits exist, but are rarely economic Grades: Cu%: 0.0-1.0 Zn%: 4.0-8.0 Pb%: 2.0-6.0 Ag (g/t):30.0-60.0 Moderate to large tonnages and moderate to high grades of zinc, lead and silver. Significance: Important source of silver, lead and zinc. Examples: Polaris, Nunavut; Pine Point, Northwest Territories Hosted: In carbonates (limestone or dolomite) Mineralization: Massive polymetallic sulphide mineralization Structures and shape: Tabular or sheet-like, 100m in length and thicknesses of 2-20 metres Mining method: Surface and underground mining Drill intersection: Metres to tens of metres with combined lead-zinc grade of >8%; silver rich deposits will have grades of >100 g/t Ag Tonnes (Mt):1.0-20.0. May be comprised of several small massive sulphide lenses Grades: Zn%: 2.0-10.0 Pb%: 2.0-10.0 Ag (g/t): 5.0-500.0 VEIN DEPOSITS (Epithermal deposits, mesothermal and intrustion-related) CARBONATE-HOSTED DEPOSITS (Skarns) Significance: World's largest source of gold and a major source of silver Examples: Yanachcha, Peru; Dome Mine, Ontario; Fort Knox, Alaska Hosted: within and near young volcanic or magmatic centres and may have a surface hotspring expression Mineralization: Can vary: gold-only, gold-silver and silver only deposits; some have excellent base metal concentrations Structures and shape: Veins, fracturs and breccias; small and narrow high-grade vein systems to large bodies with low grade mineralization Mining method: Historically, underground due to the relatively narrow veins Drill intersection: Narrow intersection <3m should have grades of 8 g/t Au or higher; large (>50 m), near-surface intersections should have grades of 1 g/t or higher; deep intersections (below 100-200 metres) should contain a minimum grade of 5 g/t Au Tonnes (Mt): Epithermal: 1.0-200.0: 1-15 are usually narrow veins Mesothermal: 2.0-20.0. Can reach 100 Mt. Intrusion: 5.0-200.0 Grades: Epithermal: Au (g/t): 1.0-15.0 with Bonanza grades of +25. Ag (g/t): 2.0-200.0 Cu%: up to 2.5% Zn%: up to 2.5% Pb%: up to 2.5% Mesothermal: Au (g/t): 4.0-20.0 Ag (g/t): 2.0-20.0 Intrusion: Au (g/t): 0.5-2.0. Higher grades are known Ag (g/t): up to 20.0 Cu%: 0.0-1.5 Zn%: 0.0-1.5 Pb%: 0.0-1.5 APRIL 2013 Grade and tonnage is highly variable Significance: A host for copper, iron, lead, zinc, iron, gold, molybdenum, silver, tin, and tungsten ore Examples: MacTung, Yukon; Ok Tedi Mine, Papua New Guinea; Antamina, Peru Hosted: Most often formed in the contact zone between a carbonate sedimentary host rock (limestone) and a granitic magmatic intrusion Mineralization: Varies depending on ore type; iron skarns consists dominantly of magnetite, copper skarns of chalcopyrite and bornite, lead and zinc skarns of sphalerite, galena and pyrrhotite; alteration minerals include garnet, pyroxenes, and epidote Structures and shape: Highly zoned, stratiform, vertical pipes, fault controlled sheets, irregular ore zones and massive lenses Mining method: Surface and underground mining Drill intersection: Notable drill intersections are metres to tens of metres in length Tonnes (Mt): >250, but averages 4 Mt of mined ore Grades: Varies for dominant ore type 2-15 g/t Au 5-10% Ag 1-2% Cu 40-60% Fe 1-2% Mo 1% Sn 10-15% Zn+Pb 0.5-2% W www.resourceworld.com 49

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