Mineral Standards - Glossary & CRM 101

ASSAY

ASSAY - In exploration and mining rock and ore samples are tested (assayed) in Assay Laboratories.The word assay comes from the French word essai, which means "trial," an appropriate sense for a word that means to examine for analysis. As a noun, assay means a test or appraisal to determine the components of a substance or object. As a verb, it refers to the act of analyzing, or of conducting that test. It is usually used in chemistry-related fields like metallurgy and pharmaceuticals, but you can also assay a poem.

ASSAY STANDARDS

BIAS DETECTION

BIAS DETECTION - Laboratory Bias is an issue in all branches of analytical science (agricultural, biological, chemical, pharmaceuticals etc). It can only be measured by inter-laboratory testing, which is the process used to characterise all mineral CRM's, and is the reason for the production and use of Matrix Reference Materials (CRM's and RM's). Laboratories use CRM's and RM's to test and calibrate their analytical methods. Bias is normally caused by differences in analytical methods, techniques, equipment and calibrations. It is also the natural result of changes to analytical methods which are being continually improved in labs that are forever getting better at catching the ball (so to speak). Labs often boast about their methods being the best. In the real world the different laboratory companies jealously guard their secrets, there is no such thing as a standardised analytical method and the only effective technical communication between different labs is when staff jump companies.

The two types of bias of concern are:

1. Within laboratory bias. Detected when a laboratories Control Sample results drift over time, indicating something in their method is not stable. The out-of-control sample batches usually need to be re-analysed.

2. Between laboratory bias. The CRM's main justification for being. Detected when two different labs consistently report different results for the same sample, hopefully slight, but often Material. Unresolved material bias between different labs can result in exploration program results being discounted, a Mineral Resource being downgraded; and operationally wildly optimistic or pessimistic mine plans.

BEST PRACTICE

BEST PRACTICE - How something is supposed to be done. Defined as the set of working methods that has has been found, through experience and research, to be the best to use in a particular business or industry. It should be described formally and in detail. Mineral Assay Laboratory competence and documentation will be accredited and tested through the National Accreditation Authority (as per ILAC system ISO/IEC 17025). A good lab will be accredited for all of the elements, methods and grades that it offers but this is not always the case and should be checked. For example a lab might be 17025 accredited for its iron ore analyses but not for platinum; for Au Pb Collection ICP finish between 5 and 10 grams per tonne"" but not for between 0.2 and 1.0 g/t.

Over and above the ISO accreditation system and relevant to mineral labs are the Best Practice Laboratory QA/QC systems developed for pathology laboratories through the work of Dr James O. Westgard. “Westgard Rules”, are multirule QC rules that use Control Samples (CRM's) to help analyze whether an analytical run is in-control or out-of-control using and should be used by both the lab and the customer to monitor that the labs Best Practice procedures are actually working.

Ideally, in the mining and exploration industries, a cost effective "Best Practice" sampling and assay program should at least be recording the following statistics for its internal Quality Management Program:

The laboratory bias (for the particular method used). This should be very low for samples close to the mine cutoff grade and for very high grade samples. It can be higher for less revenue sensitive analyses, such as for tailings or for geochem programs.
The relative standard deviation (RSD or CV) for the control sample results. It is very important to take into account that the single laboratories Control Sample RSD should be much lower than the RSD from interlaboratory testing; but the laboratory's Control Limits must still be within the Control Limits derived from the interlaboratory testing.
The error detection rate (the critical systematic error). How many of the laboratory errors identified by Control Samples turn out to be real errors on being properly investigated; and not false alarms.
The false error detection rate. How many of the lab errors identified turn out to be false alarms.

CERTIFIED REFERENCE MATERIALS (CRM'S)

CERTIFIED REFERENCE MATERIALS (CRM'S) - Reference materials that are characterised by metrologically valid procedures for one or more specified properties and which are accompanied by a certificate providing the value of the specified property, its associated uncertainty, and a statement of metrological traceability. ISO Guide 30:2015 recommends terms and definitions that should be assigned to them when used in connection with reference materials, with particular attention to terms that are used in reference material certificates and corresponding certification reports. The certificate must contain a statement of traceability indicating the principles and procedures on which the property values (together with their measurement uncertainties) are based. In the case of mineral CRM's this will be method specific, by interlaboratory testing, with operationally defined property values, using a network of competent laboratories employing methods which have been independendently validated (ISO 17034:2016).

CONTROL LIMIT

Control Limit – A window of acceptability for results obtained by a laboratory for a reference material and generally calculated from multiples of the standard deviation of the certification data. Be warned that the Control Limits published on the CRM manufacturers certificate (colloquially known as the "package insert") are calculated out of results from a number of different laboratories in the Interlaboratory Testing Scheme. The Control Sample results from a single laboratory should be much tighter but still within the Control Limits from the interlaboratory testing.

CIM CODE

CONTROL SAMPLES

CRIRSCO

CUSTOM REFERENCE MATERIALS

ILAC

ILAC - The International Organisation for Accreditation Bodies operating in accordance with ISO/IEC 17011 and involved in the accreditation of conformity assessment bodies including calibration laboratories and testing laboratories (using ISO/IEC 17025), medical testing laboratories (using ISO 15189) and inspection bodies (using ISO/IEC 17020). The aim of ILAC is increased use and acceptance by industry and governments of the results from accredited laboratories, including results from laboratories in other countries. In this way, the free-trade goal of a 'product tested once and accepted everywhere' can be realised.

ISO

ISO 9001:2008

ISO/CASCO

ISO/REMCO (Publications)

ISO/REMCO - REMCO is the ISO Subcommittee tasked with looking after Reference Materials. It was set up in 1975 to carry out and encourage a broad international effort for the harmonization and promotion of certified reference materials, their production, and applications. Note that rock standards are a very small category of Reference Materials in the overall scheme of things. There are actually five broad categories of reference materials defined by ILAC (another ISO body, see above)- pure substances, solutions and gas mixtures, matrix reference materials (including rock standards), physico-chemical reference materials (characterised for properties such as melting point, viscocity or optical density) and objects or artifacts (characterised for properties such as taste, octane number, hardness).

REMCO guides can be purchased from ISO. They are continuously being updated and changed (and are quite expensive). If an older version is being quoted it is very important to refer to the paragraph number and its year of publication. The current guides are:

ISO Guide 30:2015 -Recommends terms and definitions used in connection with reference materials (RM's), with particular attention to terms that are used in RM certificates and corresponding certification reports.
ISO Guide 31:2015 -Intended to help RM producers prepare clear and concise documentation to accompany an RM. It lists and explains mandatory, recommended and other categories of information to be used in the product information sheets and certificates. It also contains the minimum requirements for a label attached to the RM container.
ISO Guide 33:2015 - Describes good practice in using RM's and CRM's (Previously ISO Guide 32:1997), particularly in meassurement processes. These uses include the assessment of precision and trueness of measurement methods, quality control, assigning values to materials and calibration.
ISO Guide 35:2017 - Guidance for characterization and value assignment of properties of an RM, assessment of homogeneity and stability and the establishment of the metrological traceability of CRM's.
ISO/TR 79:2015 - Summarizes the state of the art of the production and certification or characterization of qualitative property reference materials (RMs). A document intended to bring together the diverse intenational wisdom on production and the nominal properties of RM's and to contribute to the ongoing general discussion.
ISO Guide 80:2014 - Guidance for the in-house preparation of Quality Control Materials (QCMs). The requirements for "in-house" QCMs are less demanding than those for an RM or CRM. Their preparation should involve homogeneity and stability assessments and a limited characterization of the material to provide an indication of its relevant property values and their variation. This document provides the quality criteria that a material should fulfil to be considered fit-for-purpose for demonstrating a measurement system is under statistical control.
ISO/TR 10989:2009 - Reference materials -- Guidance on, and keywords used for, RM categorization. The results of a study into existing classification and categorization schemes for reference materials and proposals for a harmonised scheme that would meet the needs of producers, users and the needs of modern forms of communication such as internet based catalogues and databases.
ISO/TR 11773:2013 - Global distribution of reference materials. Contains an inventory of problems and recommendations related to the transport, import and export of non-nuclear, non-radioactive reference materials, specifically for the packaging, labelling, and documenting of the shipments in order to comply with legal requirements.
ISO/TR 16476:2016 - Reference materials - Establishing and expressing metrological traceability of quantity values assigned to reference materials.

JORC

JORC - The father of the most widely accepted modern Mineral Resource and Ore Reserves reporting codes is the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (‘the JORC Code’). The original JORC Code was put together by the AusIMM after the calamatous Nickel Boom in the 1970's when the blameless bean counters suggested that the mining types should get their house in order with respect to how they described mineral deposits. To give them credit the mining professional societies involved did an exceptionally fine job. The resulting code described minimum standards for reports issued to investors and was so good that it was quickly adapted for use by some other countries, notably Canada and South Africa, whose stock exchanges quickly made their respective national JORC type codes (the CIM Code and the SAMREC Code) mandatory for listed mining company reporting. CRIRSCO was subsequently set up to oversee future development of the "JORC based" codes and to encourage the growth of their use internationally.

MATRIX REFERENCE MATERIALS

MATRIX REFERENCE MATERIALS – In our world Matrix Reference Materials are Control Samples made out of real rocks at as close to the same (grade and matrix) as the samples with the unknown properties that are being analysed. Technically defined as "samples characterised for major, minor, and trace components for use in conjunction with the analysis of real samples of the same or a similar matrix. They are normally materials that are sampled from nature". Certified natural-matrix reference materials provide the highest degree of assurance of the entire method system being in control. Nature very often conspires to make the analysts job difficult. Rocks with different grades and compositions need tweeks to the method by the analyst to get the right answer. Analysts also like to prevent high grade samples contaminating equipment used for low grade samples. They also like to know of trace elements that might be present in quantities to (for example) make the aliquots froth in the furnace, or something.

MATERIAL (financially)

MATERIAL (financially)

MATERIAL - Material in the financial world is a term used to describe whether or not something matters, normally in the sense of whether or not the shareholders need to be told of something that might impact a companies financials. The actual definition in the JSE Listing Rules is "Information that, if ommitted or misstated, could influence the economic decisions of users and includes a change in, or constituent of, a particular factor that may be regarded in the circumstances as being material and that, as a rule of thumb, would normally be equal to or exceed 10%."

METROLOGY

MINERAL REFERENCE MATERIALS

MINERAL REFERENCE MATERIALS – Reference Materials made from soils, rocks or ores for use to check assays of soil, rock and ore samples with similar grades or chemical characteristics. As opposed to, for example, other types of Reference Materials such as for those made to check tests for thermal conductivity, electrical resistivity, peanut butter, whale blubber, cigarette ignition etc.

Ni 43-101

OREAS SuperCRMs®

OREAS SuperCRMs® - The proprietary name for OREAS Matrix Reference Materials which have been certified for up to 179 analytes, enabling control over a range of analytical methods for complete ICP-OES and ICP-MS element suites within a single CRM. The comprehensive range of analytical methods and certified elements makes them extremely useful for pathfinder and litho-geochemical programs.

QA

QC

QA/QC

QUALITY CONTROL MATERIALS (QCM’s)

QUALITY CONTROL MATERIALS (QCM’s) - Samples intended for internal laboratory quality control, without formally assigned property values or uncertainties (see ISO Guide 80). Sufficiently homogeneous and stable with one or more property value that can be used for maintaining or monitoring measurement processes. Known coloquially in some areas as IRM's (Internal Reference Materials) and SRM's (Standard Reference Materials).

REFERENCE MATERIALS (RM'S)

REFERENCE MATERIALS (RM'S) - Samples sufficiently homogeneous and stable with respect to one or more specified properties, which have been established to be fit for its intended use to check results for specific methods in a measurement process. RM’s may be chemicals, solutions, gas mixtures, matrix reference materials, physico-chemical reference materials, objects or biological specimens. The essential difference between an RM and a CRM is that the CRM requires a statement of metrological traceability.

SACNASP

SACNASP - The South African Council for Natural Scientific Professions (SACNASP) was set up by the Natural Scientific Professions Act of 2003 but is now adminstered by a new version of the Act passed in 2013. SACNASP registers all Natural Science practitioners within South Africa and in the mining industry. It is relevant to all geologists and chemists writing technical reports about mineral exploration or mining or otherwise or providing a service to the South African public. This will include all geologists acting as consultants and/or writing reports for publication by JSE listed companies and all chemists signing off assay results customers or public companies. According to the Act it is illegal within South Africa to practice and provide a service to the public as a geologist or a chemist unless registered with SACNASP. The 2003 Act punished miscreants with a fine or prison. This was watered down in the 2013 Act to just a heavy fine. Registration in essence is a process whereby the qualifications of an applicant are confirmed to be true, valid and relevant to the field of practice specified. Registered geologists and chemists will list Pr.Sci. Nat. on the report after their name.

SAMREC

SEC

SEC – The United States Securities and Exchange Commission property disclosure requirements for mining companies are currently set forth under the Securities Act of 1933, the Securities Exchange Act of 1934, in Industry Guide 7 and in various opinions. There is an industry push to standardise with the rest of the world. Revisions that are broadly aligned with the CRIRSCO-based codes were proposed in 2016 and are currently out for public comment.