Tampering is the most important issue in quality control and assurance of mineral samples. There have been celebrated instances of “salting” of mineral samples in order to get exciting assay results which translate into high stock prices. Probably the Bre-X case is the best known and securities commissions have now enacted procedures that mining companies must follow. The most important of these requirements is that mining companies have a “chain of custody” procedure.

Chain of custody simply means that the samples of rock - whether from channel samples or drill hole core - are in the custody of trusted representatives of the company from the point of leaving the field in bags or core boxes until they are received by the laboratory. The sample bags or core boxes must be sealed in such a way that a seal broken without a corresponding signature in the chain of custody table which accompanies the samples is immediately recognized. At no time can the samples be available for tampering by third parties.

Of course, company employees themselves might be tempted to tamper with samples in order to increase the value of their stock. With officers and directors of the company responsible for the correct reporting of their exploration results the probability of this happening is diminished. However, to cover that possibility the Board of Directors of most public mining companies will insist on a third party review of the corporate chain of custody procedures and may pay for third party check sampling and assaying to ensure that their employees are correctly fulfilling their responsibilities.

Assay laboratories are susceptible to error as well and there must be procedures to identify the presence of these errors as early as possible. It is important to point out that most of the larger laboratory companies have third party quality designations which require them to undergo annual scrutiny by third party referees which builds confidence in the results they report. However, the mining company should also insert known and blank samples into the stream of samples being assayed in order to check the accuracy of the laboratory. It is also advisable to have a second laboratory re-assay a percentage of the original samples in order to have two results of the same sample. 

If these simple procedures are followed the chances of fraudulent tampering with company technical data will be markedly diminished and the Board of Directors will have one less issue to worry about.