http://www.bizjournals.com/sanjose/news/2014/04/21/tesla-says-gigafactory-will-source-only-north.html

Tesla Motors Inc. said it will use only minerals from North America to build the lithium-ion batteries built in its planned $5 billion gigafactory, Bloomberg reported.

The company said it won't use overseas sources for materials like cobalt, lithium and graphite so that it can minimize the environmental impact of the batteries. The move comes as countries like China begin to close graphite mines over concerns about their effect on air quality and as companies begin to reduce the use of minerals produced in war zones like eastern Congo.

The strategy may point to a possible location for the gigafactory, which the company has said will be located in one of four southwestern states. The only one with a working lithium mine in the United States is in Nevada.

Analysts told Bloomberg that Tesla may need to get graphite from mines in Canada that haven't been built yet and look to mines in Idaho and Minnesota for cobalt.

Tesla plans to cut the cost of the batteries by 30 percent and match their current worldwide production, building enough batteries for 500,000 electric cars. Much of the raw material has to be transported thousands of miles during the supply chain, adding significant environmental costs for international operations.