Gross profit before depreciation and amortization from our zinc business unit decreased by $22 million to $182 million in the fourth quarter compared with a year ago primarily due to a lower contribution from our Trail Operations. Trail's refined zinc production and sales volumes declined by approximately 10% compared with the fourth quarter of last year due to electrolytic plant operating performance, which resulted in a temporary build-up of in-process inventories. Red Dog's zinc production rose by 5% to 142,300 tonnes in the fourth quarter compared with the same period a year ago as a result of increased mill throughput. Higher lead sales from Red Dog were the result of weather-related shipping delays that deferred sales from the third quarter. This was offset by an increase in the NANA royalty rate from 25% to 30% in the fourth quarter of 2012.
Revenues
Revenues from operations were $2.7 billion in the fourth quarter compared with revenues of $3.0 billion a year ago. Revenues from our copper business unit increased by $117 million from a year ago primarily due to higher sales volumes resulting from increased production levels. Coal revenues decreased by $424 million compared with the fourth quarter of 2011 as a result of significantly lower coal prices, despite a 16% increase in sales volumes. Revenues from our zinc business unit rose by $64 million from a year ago as a result of the timing of lead sales from Red Dog and slightly higher metal prices.
Average Prices and Exchange Rates(i)
Three months Year ended ended December 31, December 31, 2012 2011 % Change 2012 2011 % Change----------------------------------------------------------------------------Copper (LME Cash - US$/pound) 3.59 3.40 +6% 3.61 4.00 -10%Coal (realized - US$/tonne) 159 253 -37% 193 257 -25%Zinc (LME Cash - US$/pound) 0.88 0.86 +2% 0.88 0.99 -11%Silver (LME PM fix - US$/ounce) 33 32 +3% 31 35 -11%Molybdenum (published price - US$/pound) 11 13 -15% 13 15 -13%Lead (LME Cash - US$/pound) 1.00 0.90 +11% 0.94 1.09 -14%Cdn/U.S. exchange rate (Bank of Canada) 0.99 1.02 -3% 1.00 0.99 +1%
(i) Except for coal prices, the average commodity prices disclosed above are based on published benchmark prices and are provided for information only. Our actual revenues are determined using commodity prices and other terms and conditions specified in our various sales contracts with our customers. The molybdenum price is the price published in Platts Metals Week.
Our year-to-date business unit results are presented in the table below:
Year ended December 31 Gross profit before depreciation and($ in millions) Revenues amortization Gross profit---------------------------------------------------------------------------- 2012 2011 2012 2011 2012 2011----------------------------------------------------------------------------Copper $ 3,142 $ 3,108 $ 1,500 $ 1,674 $ 1,129 $ 1,369Coal 4,647 5,641 2,033 3,306 1,563 2,800Zinc 2,550 2,765 480 808 373 708Energy 4 - 4 - 1 -----------------------------------------------------------------------------Total $ 10,343 $ 11,514 $ 4,017 $ 5,788 $ 3,066 $ 4,877----------------------------------------------------------------------------
