Cooked Assays

A man once told the story of a popular assayer who never failed to get spectacular results from all mineral specimens which were brought to him for testing. The town's respectable citizens became worried and conspired to send him a small fragment from the grindstone of a carpenter for assaying. When the fabulously rich results were published in a newspaper expose, the popular "assayer" was forced to get out of town as quickly as possible.

Counterfeit assay results are as old is the hills, and a favorite ploy of the crook is to point to an "assay discrepancy" once confronted with an independent evaluation of the property which he is promoting.

In 1987, the Northwest Mining Association warned that US$250 million was lost in just that year to "dirt-pile swindles", old scams based on counterfeit assay results. Sometimes called "desert dirts", these swindles continue unabated today and often prey on retirees with a lot of wealth who have little or no knowledge of mineral exploration.

As in the time of Mark Twain, certain laboratories produce data showing exceptionally high concentrations of gold and many times platinum group metals, in the vast majority of rock sent to them for assaying. Because of their dismal reputations mining professionals never use these laboratories.

Fraud artists have found a number of ways to falsify the results of an assay. Samples themselves may be salted, or an accomplice placed in the assay laboratory to add metal to the chemicals used in the analytical process. Numbers may be falsified or assay certificates counterfeited.

Closely related to the salting scam is the assertion that a deposit contains "unassayable" or "refractory" precious metals that can only be detected by using a "proprietary" technique. This is the realm of quack science, in which con men and deluded pretenders speak the language of chemistry and metallurgy without regard for the scientific method.

The con artists use whichever number of excuses to explain why conventional chemical techniques cannot find their gold. Some say that their gold is "micro-fine" or in "micro-clusters" that have chemical characteristics that prevent them from being assayed. This explanation flies in the face of overwhelming evidence that when the particles of a substance are more finely divided, it will react more efficiently with other substances and will be extracted more easily from its matrix.

Other unassayable-gold promoters declaim about "encapsulation" by other minerals, most commonly silica, argumenting that the surrounding minerals seal off the gold from assay fluxes and leaching acids. But there are lots of strong acid attacks and reactive fluxes that will destroy any "encapsulating" minerals. A third scapegoat is "interference" by other elements, which is alleged to prevent instruments that are analylical from detecting the metals of interest. The problem is well-known in analytical chemistry and a capable chemist can find ways of eliminating the elements which interfere.

Briefly, there is always a reasonable and legitimate chemical argument that can be made against a claim of "unassayable" gold. There are also a number of analytical methods, like the neutron-activation analysis, that are not sensitive to the supposed causes of unassayable metal. Nonetheless, the investor will most of the time be a layman who is unacquainted with analytical chemistry and has to keep his eyes open for red flags and other signals that a project is far from legitimate instead.

The Canadian Institute of Mining and Metallurgy published a paper debunking the myth of "unassayable" deposits in the early 1980s. The authors investigated a lot of these projects and found that in every case, the fabulous numbers reported from unconventional assaying methods were the result of technical incompetence or outright fraud.