challenges in the determining of gold content in ores

Gold has been considered as a precious element since ancient times and has been a very important factor for power, peace and war in human societies. gold is found in various forms in nature, and the type of gold found in soil and rock causes various errors in determination methods. determining the grade of gold in metal coins and jewelry is easier and with less error than determining the real content of gold in ores. the challenge of determining the gold content and the reputation of world-renowned laboratories such as acme laboratory in canada are in field of determining the real content of gold in mineral samples. in this short opportunity, after a brief review of the importance of gold throughout history, the introduction of different forms of gold in nature, different methods of determination of gold content in jewelry, electronic components and ores will be reviewed and the errors of each method will be described. based on my research experience in felez pooyan company (www.felezpooyan.com), the suitable ways to measure total gold content will be introduced, especially in mineral samples. it will be identified that the big errors of determination of cold content is related to refractory and invisible coated native golds. leaching and release of refractory gold is a difficult process and requires a complex process and sub-micrometer particles of ore. the entry of invisible coated native gold into the analytical sample solution requires a large volume of the ore sample, while it has already been ball milled into fine particles (sub-micrometer or nanoparticles).