Coarse certified reference materials, also known as bulk standards, are an integral part of a larger QA/QC system which includes pulverized reference material, blanks, and replicates from various stages of the sample mass reduction process, for monitoring analytic laboratory performance.

Pulverised reference material monitors analytical performance only, whilst coarse reference material monitors the drying and sample preparation stages for the introduction of bias. Issues commonly identified are poor LOI analysis leading to mass balance error, bias in sample mass reduction steps, loss of clays to dust extraction systems, and poor sub-sampling post pulverisation.

Our coarse reference materials are manufactured to similar analyte variances as pulverised reference materials due to the 2kg to 4kg sample mass used, which uses the volume-variance effect to produce an equally consistent product.

Clients select and supply material for production of the reference material.  Materials selected are usually based on a range of expected ore grades, or by a combination of expected economic and deleterious analyte ranges. The objective in material selection is ensuring reference material is matrix matched to the production material being tested. Examples of this would include not only ore grade and mineralogy and deleterious elements, but also host rock such as clay content, or particle size distributions. Blending of various source rock to achieve a target grade is also possible.

In addition, mine site specific waste rock is commonly selected for use as “blanks” to test for cross-contamination or smearing between samples within sample preparation equipment. This allows a better estimation of smearing than an abrasive gravel which is likely to over-report cross-contamination, especially if a smaller sample mass is used in the blank than the common samples.