Because tungsten minerals are heavy, exploration can be done using stream sediment samples. Prospectors looking for gold have found scheelite or wolframite in their placer concentrates, and in some cases this has led them to make important tungsten finds.

While some future cobalt will come from recycling lithium batteries and other products, the coming huge need for cobalt is virtually a perfect storm of heavy demand and insufficient supply.

These were the men who periodically picked up the gold amalgam from the tables and sluices in the dredge, processed it, and transported the gold ingots to the railroad express office in Alder. Their trustworthiness must have commanded a prominent wage.