Gold by Fire Assay
An optimal fire assay flux recipe and rigorous quality control program easily handle problem materials including chromite, base metal sulfides and oxides, selenides, and tellurides. Choice of crushing fineness, splitting technique and pulp size can all affect the analytical outcome of fire assay gold methods. Discuss with your local ALS laboratory for more information.
Trace level and low-grade silver samples may be analyzed by acid digestion for maximum sensitivity and precision. Multi-element packages including Ag are listed in the Targeted Exploration section. Because silver can suffer from nugget effect, occasional duplicate analysis may help detect sampling error at these low levels. At higher grades, fire assay with larger nominal weights may be preferable.
Super Trace Gold in Soils & Sediments
ALS offers the lowest detection limits in the industry for gold in soils and sediments by both cyanide and aqua regia digestion, using our innovative super trace analytical methodology. Full multi-element geochemical suites may be read from the same digest solution as our aqua regia and ICP-MS super trace gold method. This package mirrors our ME-MS41L method, with slight adjustments made to accommodate the larger nominal sample weight necessary for representative gold analysis.
Platinum Group Elements
Platinum, palladium, rhodium and gold may be determined by standard lead oxide collection fire assay and ICP-MS or ICP-AES finish. For the full list of platinum group elements, nickel sulfide collection fire assay must be used for a quantitative analysis.
Precious Metals in Concentrates and Bullion
High precision analysis and umpire assay of precious metals in concentrates and bullion are performed by the most senior fire assay technicians and checked by certified assayers to ensure accuracy. Minimum sample weight required varies, contact your local lab.
Low Level Gold in Soils & Sediments
Our trace level methods by aqua regia digestion and ICP-MS finish are excellent for regolith, where gold anomalies indicating mineralization below surface are well-characterized. Aqua regia dissolves native gold as well as gold bound in sulfide minerals; however, depending on the composition of the soil, gold determined by this method may or may not match recovery from fire assay methods. As with our super trace methods, multi-element packages can be read from the same digestion solution as trace level gold for a complete exploration tool.