Industry in Panama is dominated by mining, construction, and milling. The sector's growth rate was 4.6 percent in 1999. Mining continues to expand in importance. In 1999, mining was worth US$25 million. In 1991, there were only 20 mining operations in the nation, but by 1999 there were 120 mining projects. The key mineral produced was gold. In 1997, 1,550 kilograms of gold were mined. The nation has 2 billion tons of proven copper reserves. There are 2 major copper mines set to begin operations. At Cerro Colorado, the mine is estimated to be worth US$150 million and another, at Petaquilla, is estimated at US$800 million.