China used to have an insatiable appetite for copper, but now it is dropping at a steep curve, destroying raw material prices and killing U.S. jobs.

Copper is a key indicator of global growth and it is hit hard by China's economic downturn. Prices have slide down 40 percent since 2013. And as the huge demand for the metal in China fizzled down, the world is experiencing an oversupply of copper.

Copper is used for electronic products, cars, wiring, building construction, and plumbing. All of which are needed in China's massive infrastructure development boom in the last ten years. But now, that building boom is going down. This has caused miners to react by decreasing mining activities, making them cut U.S. jobs.

The biggest publicly traded copper miner in the world, Freeport-McMoRan is cutting U.S. mining employees and contractors by 10 percent, which is about 800 jobs in Arizona and 200 in New Mexico. It plans to suspend operations in its Arizona mine called Miami and decrease its output in its New Mexico mine Tyron by 50 percent.

The mining firm drastically scaled back its 2016 capital spending plans by 29% Thursday. According to the company, it is scaling back its spending budget on oil-and-gas projects because of the drop in energy prices.

Last Wednesday, Copper was in a six-year low after the Chinese stock market chaos. Some 40% of the world's copper go to China. But there are reports stating that Copper prices rebounded Friday after gains in Chinese stocks gave investors a little confidence on the Chinese economy.

Copper is the most actively traded contract. During the December delivery, it increased 6.05 cents, or 2.7%, to $2.2955 a pound in New York Mercantile Exchange's Comex division.

The slowing of the Chinese economy is taking its toll on the U.S. with all the mining jobs gone.