Mercury was a critical element in pre-twentieth century gold mining. Gold has an affinity for mercury, not a chemical bond, just a curious tendency to attach.
Tables smeared with a mercury coating were placed in front of the stamp mills. The mined rock, smashed to sand by the stamps, would bounce across the tables with the gold particles sticking to the mercury and the waste rock traveling off the end of the table into the waste pile. Periodically, the tables would be scraped clean and the gold-laden mercury sent for refining.
Today, mercury is mostly used by hobby miners, especially for placer clean-up. But watch out! Mercury is toxic! It is easily ingested, inhaled during retorting (distilling to recycle), or absorbed through the skin. Two MILDER symptoms of mercury poisoning are loss of short term memory and loosening of the teeth. Need we go on?
Gold, although electrically conductive, is chemically inactive and so it is most often found as a native element. It will, however, react with the element Tellurium to form gold Telluride minerals, none of which look like gold. Gold Tellurides are important in Colorado mining history and are major gold sources at Cripple Creek, Boulder County, and camps in the San Juan Mountains, including Telluride.
Prospecting manuals and historical accounts will tell you that the test for any Telluride mineral is to toss some into a hot frying pan. If there is a puff of white smoke, then it may be a gold Telluride. What may not be mentioned is that Tellurium fumes are TOXIC!
Early miners who roasted gold Telluride ores to recover the gold sometimes poisoned themselves. An early symptom of Tellurium poisoning is "Telluride breath," which is offensive to others past the point of nausea. It is a permanent condition which will gaurantee a lifetime of solitude. The lifetime may also be short.
If you want to use mercury or try documented "nifty" field tests, at least investigate what you are doing first. As they say, "You won't make the same mistake twice!"