Tellurium at Eau Claire The Eau Claire deposit contains a significant amount of tellurium as well as free gold. There is a positive correlation of gold and tellurium with multiple vein intersections containing in excess of one ounce of tellurium per ton (Table 1). Tellurium is one of the rarest metals on earth and is most frequently recovered as a byproduct from refining copper. Tellurium is used in semi-conductors and ceramics. It is often alloyed with cast iron, copper and stainless steel and added to lead to prevent corrosion. Increasingly, tellurium is being used to tint windows for "smart-heating" used in the manufacture of solar cells, CD's, DVD's, Blu-ray disks and flash drives. Recent advances in computer memory technology include a new application utilizing tellurium in "phase change memory chips" that can hold large amounts of data in a small space, replacing conventional memory chips. The price of tellurium over the past five years has varied from $10 to $180 per pound, however the demand from this new technology is likely to put pressure on the world's limited supply, causing an increase in tellurium metal price.
Article on Tellurium
https://pics.uvic.ca/research/tellurium-based-battery-technology-shows-promise-extend-range-electric-vehicles