OREAS 461

OREAS 461 is an ore grade, rare earth element (TREO = 1.06%)
matrix-matched certified reference material (MMCRM) prepared and certified by
Ore Research & Exploration. The materials constituting OREAS 461 were
sourced from both a quarry north of Melbourne (weathered barren siltstone) and
Lynas Corporation’s Mount Weld Project (the ‘Central Lanthanide Deposit’) which
is located 35 kilometres south of Laverton in Western Australia. The Mount Weld
source materials (waste, low and medium grade REE ores) were found to be highly
hygroscopic to the extent that significant analytical errors would likely result
during analysis unless strict moisture handling procedures were adhered. To
avoid this complication, the hygroscopic property was destroyed by roasting the
materials at 900°C for 2 hours. Following re-equilibration of the materials to
laboratory atmosphere the hygroscopic moisture content was deemed acceptable
(~0.5% H2O-).
OREAS 461 is one of six MMCRMs ranging TREO 0.53 – 9.88% and contains 113
certified values (and 50 indicative values) including REE’s, majors and traces
by fusion XRF, fusion ICP and 4-acid digestion.
A summary of the mineralogy and supergene enrichment processes that operated
in the host lateritic rocks is given in the Certificates of Analysis. Two
‘Datapack’ files are provided. The ‘Elemental’ version contains all Certified
Values in their elemental form while the other Datapack shows some of the
Certified Values in oxide format. This includes the fusion XRF group and the
majors and REE’s (and a few other associated metals) in the fusion ICP
group.