Salting (confidence trick)

In mineral exploration, salting is the process of adding gold or silver to an ore sample to change the value of the ore with intent to deceive potential buyers of the mine. In the US state of Arizona it is a class 6 felony. A famous example of salting is the former Canadian gold company Bre-X, which salted its drill core samples, leading investors to believe that they were in possession of one of the largest gold reserves ever discovered. Salting is an example of a confidence trick.

...
Wikipedia