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Rosemont Historical Reserves & Resources¹ HUDBAY Category Proven HISTORICAL MINERAL RESERVES AS AT JULY 24, 2012 Probable Total Historical Reserves Tonnes 279,481,000 325,798,000 605,279,000 Cu (%) Mo (%) Ag (g/t) 0.46 0.015 4.11 0.42 0.014 4.11 0.44 0.015 4.11 HISTORICAL MINERAL RESOURCES AS AT JULY 17, 2012 Category Inferred Note: Totals may not add up correctly due to rounding. Tonnes 116,562,000 Cu (%) 0.40 Mo (%) 0.013 Ag (g/t) 3.57 1. Source: Hudbay company disclosure, Augusta Resource Corporation's NI 43-101 Technical Report on the Rosemont Copper Project dated August 28, 2012. Hudbay is treating Augusta's publicly disclosed estimated mineral reserves and resources at the Rosemont project as a "historical estimate" under NI 43-101 and not as current mineral reserves or mineral resources, as a qualified person has not done sufficient work for Hudbay to classify Rosemont's mineral reserves or resources as current mineral reserves or mineral resources. Hudbay is currently reviewing Augusta's estimates of the mineral reserves and resources at Rosemont as well as the assumptions underlying Augusta's 2012 feasibility study. Historical reserves and resources shown on 100% basis and include sulfide zone only. The key assumptions, parameters and methods used by Augusta to prepare the historical estimate were the following: The Rosemont mineral reserves are effective as of July 24, 2012 and reported on a Net Smelter Return (NSR) cut-off of $4.90 per ton. NSR values are based on the following long term metal prices: copper price of $2.50 per pound; silver price of $20.00 per ounce; and molybdenum price of $15.00 per pound. Proposed pit operations are based on 50 foot high benches using large-scale mining equipment, including: 12.25 inch diameter rotary blasthole drills, 60 cubic yard class electric shovels, 25 and 36 cubic yard front-end loaders, 46 cubic yard hydraulic shovel and 260 ton off-highway haul trucks. Total material mined from the open pit is 1.9 billion tons, which includes 1.24 billion tons of waste material, resulting in a stripping ratio of 1.9:1.0 (tons waste per ton of ore). Contained metal in the sulphide proven and probable mineral reserves is estimated at 5.88 billion pounds of copper, 80 million ounces of silver, and 194 million pounds of molybdenum. Oxide resources are considered as waste material and are not part of the mineral reserves. Mine life is 21 years, with sulphide ore delivered to a processing plant at an initial rate of 75,000 tons per day. An expansion to the processing plant in Year 5 gradually increases daily mill throughput to 88,000 tons per day by Year 7. Increases in plant operating availability boosts the daily throughput rate to 90,000 tons per day by Year 12. During the 21 month pre-production period a total of 99 million tons of waste is stripped and 6 million tons of ore is moved to the ore stockpile. Peak mining rate of 343,000 tons mined per day is achieved in Year 3, followed by reduced rates of 285,000 tons mined per day in Years 5 to 10, and further reduced to 232,000 tons mined per day in Years 11 to 15 as the stripping ratio decreases. The mineral reserve and mineral resource estimate includes drill and assay information up to March 2012 for a total of 266 drill holes, representing 342,700 feet of drilling. 40 40

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