ed ▁for ▁ 4 % ▁of ▁total ▁exports . ▁ ▁All ▁min eral ▁comm od ity ▁production ▁increased ▁during ▁the ▁year ▁with ▁the ▁exception ▁of ▁cru de ▁pet role um , ▁which ▁decre ased ▁by ▁about ▁ 5 1 % ▁to ▁ ▁compared ▁with ▁ ▁in ▁ 2 0 0 6 . ▁C ement ▁production ▁increased ▁by ▁ 1 4 . 6 % ▁to ▁ 4 0 9 , 5 1 3 ▁metric ▁tons ▁( t ) ▁compared ▁with ▁a ▁re vised ▁ 3 5 7 , 2 3 9 ▁t ▁in ▁ 2 0 0 6 . ▁Gy psum ▁production ▁increased ▁by ▁ 8 . 9 %; ▁iron ▁ore ▁production , ▁by ▁ 6 . 8 %; ▁salt ▁production , ▁by ▁about ▁ 3 5 . 5 %; ▁and ▁ ▁cru de ▁steel ▁production , ▁by ▁about ▁ 4 . 2 %. ▁The ▁sharp ▁increase ▁in ▁co pper ▁and ▁gold ▁production ▁was ▁ow ing ▁to ▁the ▁opening ▁of ▁the ▁Gu el b ▁Moh gre in ▁Mine ▁in ▁late ▁ 2 0 0 6 . ▁ ▁M ining , ▁which ▁was ▁one ▁of ▁the ▁country ’ s ▁most ▁important ▁se ctors ▁to ▁the ▁national ▁economy , ▁contributed ▁about ▁ 1 2 % ▁of ▁the ▁gross ▁domestic ▁product ▁( G DP ) ▁and ▁represented ▁more ▁than ▁one - half ▁of ▁the ▁country ’ s ▁export ▁ear nings ▁in ▁ 2 0 0 5 . ▁according ▁to ▁the ▁Min ist ère ▁des ▁M ines ▁et ▁de ▁l ’ indust rie ▁( MM i ), ▁the