In 2010 , China produced over 95 % of the world 's rare earth supply , mostly in Inner Mongolia , although it had only 37 % of proven reserves ; the latter number has been reported to be only 23 % in 2012 .
China had produced over 95 % of the world 's rare earth supply . Most of this has been done in Inner Mongolia , even though it had only 37 % of proven reserves .