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.