salt

To salt a mine is to deliberately introduce high-grade ore or mineral into a sample location, then extract and assay that material to create false evidence of valuable deposits. The term originated in gold prospecting but applies across hard rock mining: a prospector or claim holder salts a prospect hole by placing ore retrieved from elsewhere into the blast zone, ensuring that drilling or sampling returns artificially rich results. This deceives potential investors, claim buyers, or financing partners into believing the property contains economically viable ore grades.

The mechanics are straightforward and difficult to detect without careful oversight. A small quantity of high-grade ore or concentrate, sometimes just a few ounces of gold or silver-rich material, is placed in a drill hole or blast rubble before the hole is sampled. When the core or chips are collected and sent to an assay laboratory, they show spectacular values: 2 or 3 troy ounces of gold per ton, for instance, when the surrounding rock actually carries 0.1 ounces per ton or less. The salted sample is then presented as representative of the deposit.

Detection and historical context

Mining engineers and geologists combat salting through independent sampling protocols: taking samples from multiple locations, using locked core boxes, documenting drill cuttings in real time, and employing third-party assayers. A salted property typically fails during due diligence when adjacent holes or bulk sampling returns nothing near the initial grades. The practice became rampant during gold rushes and penny stock booms when capital flowed toward claims with minimal geological work. Regulations requiring documented drilling and sampling chains of custody have reduced casual salting, though motivated fraud persists in jurisdictions with weak oversight.

The verb extends beyond ore placement: in oil exploration, a similar con involved adding crude to a dry well's wall to suggest hydrocarbon presence. In industrial minerals, salting manifests as seeding a sample pit with higher-quality material. The word itself likely derives from the culinary practice of salt enhancing or adulterating food, suggesting enrichment through addition rather than honest assessment.

Salting represents a category of assay fraud distinct from sampling bias or natural grade variation. It is deliberate, material misrepresentation intended to secure financing or a sale. Once discovered, it destroys a property's reputation and the perpetrator's standing in the trade. Insurance claims and criminal charges follow proven instances, making the short-term gain of duping investors a severe long-term liability in mining.