World demand is projected to rise to at least 185,000 tonnes annually by 2015. But the global supply of rare earth has been the centre of intrigue and controversy.  –  Although many of the rare earth metals are not necessarily rare to find — some are more abundant in the earth’s crust than lead, gold, copper or platinum — they often exist in very small concentrations, making extraction difficult. And because of their similar chemical properties, rare earths tend to clump together, usually with radioactive elements such as thorium and uranium, making separation complicated and expensive.”