Quality assurance (QA) and quality control (QC) are the two major components of any quality management system. According to ISO’s definition, QA is “the assembly of all planned and systematic actions necessary to provide adequate confidence that a product, process, or service will satisfy given quality requirements,” and QC refers to “the system of activities to verify if the quality control activities are effective.” While QA deals with prevention of problems, QC aims to detect them, in the event that they occur.
Quality control reporting requirements by the mining industry
In practical terms, geological quality control procedures are intended to monitor precision and accuracy of the assay data, as well as possible sample contamination during preparation and assaying.
NI 43-101 Standards of Disclosure for Mineral Projects requires exploration and mining organizations with Canadian investors to report their QA/QC program. The relevant sections are as follows.
Section 3.3 of NI 43-101 – Requirements Applicable to Written Disclosure of Exploration Information: The issuer (company) must include a description of the quality assurance program and quality control measures applied during the execution of the work being reported on.
Section 1.5 of Companion Policy 43-101CP provides guidance to a qualified person classifying a mineral deposit as a mineral resource or mineral reserve to follow the Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines adopted by CIM. The section relevant to QA/QC in those guidelines follow.
The resource database–QA/QC: This program should be concerned with, but not limited to data verification, drill sample recovery, sample size, sample preparation, analytical methods, the use of duplicates/blanks/standards, effects of multiple periods of data acquisition and consistency of interpretation in three dimensions.
Item 15 of Form 43-101F1 Technical Report – Sample Preparation, Analy-ses, and Security. Describe sample preparation methods and quality control measures employed before dispatch of samples to an analytical or testing laboratory, the method or process of sample splitting and reduction, and the security measures taken to ensure the validity and integrity of samples taken. Include:
• A summary of the nature and extent of all quality control measures em-ployed and check assay and other check analytical and testing procedures utilized, including the results and corrective actions taken.
• A statement of the author’s opinion on the adequacy of sample preparation, security, and analytical procedures.
Internal lab procedures
Competently managed laboratories have their own internal QC protocols, and the assay certificates commonly include the results of at least some of the internal laboratory QC. However, laboratories will commonly reveal those checks that pass their internal controls, but not the failures. Results of batches that fail laboratory QC are re-run, and the re-run results, along with new passing QC results, are reported. Thus the laboratory QC provides a picture of what the laboratory considers acceptable performance, rather than a direct measurement of the quality. Independent measurements of the data quality are typically poorer than the QC reported by the laboratory because they detect some instances of poor performance that slipped through the laboratory QC. How different these results are depends upon how effective the laboratory QC was at eliminating poor performance. Thus the external QC provides an assessment of the efficacy of a laboratory’s QC, as well as an independent assessment of the data quality.
AMEC regards sole reliance on the internal laboratory QC as unacceptable practice. This has been proven by AMEC’s direct experience in revealing deceptive practices by laboratories generally considered to be ‘professional.’ Regardless of the intentions of laboratory management or laboratory owner management, the incidence of poor sample preparation practices and unreported blank, duplicate, and Certified Reference Material (CRM) failures is actually higher than commonly acknowledged.
Quality control in the real world
AMEC’s experience with numerous recent audits and due diligence studies conducted on projects in South America, Asia, Africa, North America, and Europe (many of them managed by North American and Australian exploration and mining companies) indicate that comprehensive geological quality control programs are still infrequent. Out of 26 projects from South America and Europe audited or reviewed by AMEC between 2003 and 2007, only four had established QA/QC programs that would allow precision and accuracy to be properly assessed.
Additional evidence comes from a recent review of industry QA/QC practices in NI 43-101 technical reports. AMEC could not find relevant details on QA/QC programs in half of the consulted SEDAR-filed technical reports.
Although the overall cost increase of the implementation of a QA/QC program is relatively small, usually not exceeding one to two per cent of the total exploration costs, the percentage increase to the assay budget evokes a negative response by the cost-conscious company.
As a result of disclosure standards in place and the expected scrutiny by due diligence providers for investment banks in support of a finance, junior and major companies should be increasingly interested in implementing effective QA/QC programs. Confidence in the analytical data mandates it.
About the Author
Armando Simón is principal geologist, AMEC International (Chile) S.A., and Greg Gosson is technical director, geology and geostatistics, AMEC Americas Limited.