(1) A reconciliation of this non-GAAP measure to cost of sales and other direct production costs and depreciation, depletion and amortization, the most comparable GAAP measure, can be found in  Reconciliation of Total Cash Costs to Costs (non-GAAP) of Sales and Other Direct Production Costs and Depreciation, Depletion and Amortization (GAAP). The $45.2 million decrease in gross profit for 2012 compared to 2011 was primarily the result of lower average prices for silver, zinc and lead, partially  offset by higher gold prices in 2012. Average prices for silver and gold were higher in 2012 by 55% and 36%, respectively, compared to their levels in  2010. The impact of higher precious metal prices was offset by lower average zinc and lead prices and higher mining and milling costs, as discussed  further below, when comparing gross profit for 2012 to 2010. Results for 2012 were also impacted by marginally lower silver, zinc, lead, and gold  production. Gross profit at Greens Creek was also impacted by positive price adjustments to revenues of $4.9 million in 2012 compared to negative  prices adjustments of $6.7 million in 2011 and positive adjustments of $12.8 million in 2010. Price adjustments to revenues result from changes in  metals prices between transfer of title of concentrates to buyers and final settlements during the period. The impact of positive price adjustments was  partially offset by a net loss of $1.3 million on forward contracts related to concentrates shipped during 2012 compared to a gain of $6.2 million in 2011  and a loss of $2.1 million in 2010. Mining costs per ton increased in 2012 by 30% and 49% compared to 2011 and 2010, respectively. Milling costs per ton decreased slightly in 2012 by  4% compared to 2011 and increased by 21% compared to 2010. The higher mining costs were due primarily to increased use of contract miners at  Greens Creek, which is more expensive than internal labor; however, the cost of internal labor also increased during 2012. The increase in mining costs  in 2012 is also due to higher maintenance costs. Milling costs are down in 2012 compared to 2011 because we generated less power on-site in 2012  due to higher availability of less expensive hydroelectric power, the result of higher precipitation levels in Southeastern Alaska. The increase in milling  costs in 2012 compared to 2010 is primarily the result of an increase in the cost of diesel fuel from $2.66 in 2010 to $3.66 in 2012. The Greens Creek operation is partially powered by diesel generators, and production costs have historically been significantly affected by  fluctuations in fuel prices and utility power availability. Installed infrastructure allows hydroelectric power to be supplied to Greens Creek by Alaska  Electric Light and Power (AEL&P) via a submarine cable from North Douglas Island, near Juneau, to Admiralty Island, where Greens Creek is located.  This has reduced production costs at Greens Creek to the extent power has been available. During 2009 and 2010, the mine began receiving an  increased proportion of its power needs from AEL&P; however, in 2011, due to lower precipitation, less hydroelectric power was available. During 2012,  the mine again received an increased proportion of its power needs from AEL&P. When weather conditions are not favorable to maintain lake water  levels, the mine relies on diesel generated power. Fuel costs represented approximately $6.8 million (6% of total production costs) at Greens Creek in  2012 compared to $12.7 million (13% of production costs) in 2011 and $5.1 million (6% of production costs) in 2010. The cost of hydroelectric power was  $6.8 million (6% of production costs) in 2012, $3.9 million (4% of production costs) in 2011, and $6.2 million (7% of production costs) in 2010. The chart below illustrates the factors contributing to the variances in total cash costs per silver ounce for 2012 compared to 2011 and 2010: Mining and milling cost per ounce increased in 2012 compared to 2011 and 2010 due to increased use of contract miners, higher maintenance costs  in the first half of 2012, and the effect of lower silver production on cost per ounce, partially offset by lower power costs. Other cash costs per ounce for 2012 were higher compared to 2011 and 2010 due to the effect of lower silver production and higher labor costs,  partially offset by lower mine license tax. Treatment costs were slightly lower in 2012 compared to 2011 as a result of lower zinc concentrate production and lower zinc and lead prices.  Treatment costs include a price participation component that fluctuates with changes in base metal prices. In 2012, treatment costs were higher  compared to 2010 due to an increase in base treatment charges. In addition, we incurred additional refining charges for shipments sent to China. 24 [ HL:10-K ]  Year 2012 2011 2010 Cash cost per ounce $ 2.70 $ (1.29) $ (3.90) $ 11.53 mining and milling 2011 2012 2010 $ 9.50 $ 7.47 $ 7.44 other cash costs 2011 2012 2010 $ 6.69 $ 5.98 $ 11.47 treatment costs 2011 2012 2010 $ 12.18 $ 10.24 $ 2.11 concentrate freight 2011 2012 2010 $ 2.03 $ 2.14 ($ 29.85) by-product credit 2011 2012 2010 ($ 31.69) ($ 29.73) Years Ended December 31 ($ per ounce produced)