OREAS 725b

OREAS 725b is a certified reference material (CRM) prepared from a blend of granodiorite sourced from Oaklands Quarry in Tullamarine, northern Melbourne (Victoria); a high-grade synthetic graphite concentrate; and a vein-type natural graphite concentrate from central Sri Lanka.

The granodiorite is typical of Silurian granitoid units in the Melbourne Zone of Victoria. The natural graphite concentrate was derived from vein-type graphite mineralisation sourced from the Queens Graphite Mine (QGM), located in the Matale–Kurunegala Project area in central Sri Lanka. The synthetic graphite component is a fine powder sourced from a commercial supplier. It is intended to simulate natural graphite ore and enhance the carbon concentration of the CRM.

OREAS 725b has been characterised for Total Graphite Carbon (TGC) by dilute acid (HCl) digestion followed by roasting at approx. 425 °C, then analysis by infrared combustion furnace. Nineteen commercial analytical laboratories participated in the certification program of this CRM.

Homogeneity was evaluated using 12 subsamples analysed in a single laboratory. ANOVA was applied to duplicates from six test units to compare within- and between-unit variances, providing a statistical measure of batch homogeneity.