OREAS 270

OREAS 270 is a low-level gold certified reference material produced from a blend of barren mudstone–hornfels units and finely disseminated low-grade Blackwood gold mineralisation sourced from central Victoria, Australia.  These materials provide a robust, well-behaved matrix suitable for quality control of low-level gold determinations.

The dominant component of the matrix is barren Mansfield hornfels, a fine-grained, metamorphosed mudstone–siltstone unit representative of Victorian sediment-hosted sequences. The barren backbone is complemented by scoria and two distinct Blackwood mineralised units.

OREAS 270 has been characterized using the following methods:

• Gold by Pb collection fire assay (25-50g charge weight) with AAS and ICP-OES finish
• Gold by Bi collection fire assay (30 g charge weight) with AAS finish
• Gold by 15-50g aqua regia digestion with ICP-MS and AAS finish
• Gold by Bulk Leach Extractable Gold (BLEG) with low-level instrumental finish
• Full ICP-OES and ICP-MS elemental suites by 4-acid (HNO3-HF-HClO4-HCl) digestion
• Full ICP-OES and ICP-MS elemental suites by aqua regia digestion

Certified values for applicable analytes are operationally defined for each method, with results under OREAS ISO 17034 scope of accreditation.