Sample Weight: 15 g
Gold is determined in geological materials by lead fusion fire assay and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). The sample is mixed with fluxing agents to assist with melting and promote separation from waste (gangue) materials from the precious metals. After cooling, the gangue is separated and discarded as a glassy slag from the precious metal containing lead button. This button is further heated on an absorbing magnesium oxide crucible to remove the lead and trace amounts of base metals. A small silver prill is left containing the precious metals. The silver prill is digested in aqua regia then analyzed by ICP-OES and ICP-MS. Lower concentrations of Gold are measured by ICP-MS. Higher concentrations are measured by ICP-OES.
The reporting limit range for Gold is 1 ppb to 10,000 ppb.
Data will be deemed acceptable if recovery of Gold is ±20% at five times the Lower Limit of Determination (LOD) and the calculated Relative Standard Deviation (RSD) of duplicate samples is no greater than 20%.
Central Mineral and Environmental Resources Science Center