Not-so-Rare Earths
News reports say that China -- supplier of over 95% of the world's "rare earths" -- is curtailing these exports. Since rare earths are used in devices that have military uses, this got me wondering if China is simply the cheapest producer or if it actually has a lock on geological deposits. Via the Wikipedia , I found detailed information in a USGS report (2010-5220 ). Most rare earths are in more abundant supply than gold, platinum, silver or mercury. Indeed, their average concentration in the earth's crust is higher than copper. However rare-earths are more dispersed than copper, so areas with high concentrations -- making mining economical -- are more rare. Still, they have been mined all over the world. "Until 1948, most of the world's rare earths were sourced from placer sand deposits in India and Brazil....Through the 1950s, South Africa took the status as the world's rare earth source. Through the 1960s until the 1980s, the Mountain Pass