Tailings are materials produced from mining such as milled rock and effluents. In many cases, massive quantities of these materials, regarded as waste, are left from previous operations. In the past, despite the best of efforts, ore processing mills did not achieve 100% recovery rates. The failures of past technologies to extract all the metal from mined ore presents extremely profitable opportunities for those who are able to economically reprocess waste materials. In addition, the many highly valuable rare earth elements materials that have been proven to co-exist with gold deposits can also now be reclaimed.
There are hundreds of good mining properties out there, many with large tailing piles, which were owned or mined only for the metallic gold because the owners did not know of, nor test for, gold Compounds. To this day most tailing piles still contain up to 5 times as much gold (in the form of compounds) as was extracted during the original mining operations.