OREAS 261 was prepared from a blend of gold-bearing oxide ore from one of the Sepon gold deposits and barren mudstone sourced from a quarry east of Melbourne, Australia. The Sepon Mineral District stratigraphy comprises Devonian to Carboniferous aged continental fluvial and shallow to deep marine sediments deposited in a half graben basin. Gold mineralisation is localised in structural and stratigraphic fluid traps similar in style to the sediment-hosted gold deposits of the Carlin Trend, Nevada, USA. Mineralisation is finely disseminated and closely associated with decalcification and variable silica replacement of calcareous rocks along structures and at lithological contacts.
The Sepon deposit is located approximately 40 kilometres north of the town of Sepon, in Savannakhet province of south-central Laos. OREAS 261 is one of a suite of four oxide gold CRMs ranging in gold content from 16 to 214ppb.
| CRM Code |
Principle Certified Values |
State |
Matrix |
Mineralization |
| OREAS 261 |
Au 49ppb |
Cu 64ppm |
Ag 0.204ppm |
oxide |
mudstone |
carlin style |