of freight charges. Although we achieved lower unit costs at most of our copper operations, unit costs increased  significantly at our Quebrada Blanca Operations and accounted for approximately $100 million of the increase in cost  of sales in 2012. This was due to significant increases for labour costs, reflecting new terms of the collective agreement  ratified early in 2012, and higher contractor and consumable costs. We also incurred one-time labour settlement costs  at various operations totalling $103 million in 2012 compared with $84 million in 2011.  Comparing 2011 with 2010, the higher costs were due mainly to the new copper concentrator at Carmen de Andacollo  operating for a full year in 2011, compared with three months in 2010, as commercial production commenced  October 1, 2010. This accounted for approximately $250 million of the increase in cost of sales in 2011. We also  incurred one-time labour settlement costs at Highland Valley Copper and our coal operations totalling $84 million in  2011. The balance of our higher costs of sales was partly due to increased energy costs, consumables and the use  of contractors to maximize production at our coal operations. In addition, the cost of concentrate purchases at our  Trail Operations increased by approximately $400 million, due to higher metal prices, especially for silver, and as a  result of our Trail Operations operating at higher production levels compared with 2010. In 2012, our depreciation expense was $951 million compared with $911 million in 2011 and $916 million in 2010.  Increased throughput and production levels at our coal and copper operations, the commencement of the amortization  of Antamina’s major expansion project and Highland Valley’s two-year waste stripping campaign and buttress  placement project were the main reasons for the higher depreciation expense in 2012. However, this was partially  offset by the effect of an increase in our coal reserves, which reduced our per-unit amortization rate and our overall  depreciation charge for coal. We expect that these increased reserves will have a more significant effect in reducing  the depreciation charge in 2013. Other Expenses We must continually replace our reserves as they are depleted in order to maintain production levels over the long  term. We try to do this through our exploration and development program and through acquisition of interests in new  properties or in companies that own such properties. Exploration for minerals and oil is highly speculative and the  projects involve many risks. The vast majority of exploration projects are unsuccessful and there are no assurances  that current or future exploration programs will find deposits that are ultimately brought into production. We have  expanded our exploration activities in 2012 and 2011, resulting in the costs being significantly higher than in 2010. Our research and development expenditures are primarily focused on advancing our proprietary CESL hydro- metallurgical technology, the development of internal and external growth opportunities, and the development and  implementation of process and environmental technology improvements at operations. Other operating income and expenses include items we consider to be related to the operation of our business, such  as final pricing adjustments (which are further described in the next paragraph), share-based compensation, gains or  losses on commodity derivatives, gains or losses on sale of operating or exploration assets, and provisions for various  costs at our closed properties. Significant items in 2012 include $24 million from gains on the sale of assets, $45 million  of positive pricing adjustments and a $34 million expense for share-based compensation. Significant items in 2011  include $130 million of gains on the sale of assets, $210 million of negative pricing adjustments, and a $21 million  55 Generations ($ in millions) 2012 2011 2010 General and administrative $ 136 $ 125 $ 137 Exploration 102 105 56 Research and development 19 17 20 Other operating expense (income)  24 174 (640) Finance income (135) (113) (95) Finance expense 577 595 691 Non-operating expense (income)  848 (197) 418 Share of losses of associates 10 5 5 $ 1,581 $ 711 $ 592