Fire assay for gold
Process photograph used for illustration.
What is fire assay?
Fire assay is an established laboratory technique for determining gold in a prepared sample. In a common lead-collection process, the sample is fused with flux and a collector; subsequent separation produces material for measurement by a gravimetric or instrumental finish.
The result starts with the sample
A laboratory result applies to the material actually tested. A carefully performed assay on an unrepresentative piece may not describe the lot you intend to buy. Agree how the sample will be obtained, identified and handled before analysis.
Questions before destructive testing
- Who selects and takes the sample, and can the parties witness it?
- How much material is required and consumed?
- Will melting, drilling or cutting be necessary?
- Will a sealed split or retained sample be available?
- How will sample identifiers connect to the original lot?
- What method, units and reporting basis will appear on the report?
XRF and fire assay answer different questions
| Question | XRF screening | Fire assay |
|---|---|---|
| What is measured? | Composition at a tested surface region | Gold in a prepared test portion |
| Material consumed? | Measurement can be non-destructive; preparation may mark an item | Destructive test portion |
| Main concern | Surface may differ from the interior | Sample must represent the intended material |
Turnaround and fees
Do not assume a universal turnaround or price. Sample preparation, the analytical finish, quality-control work and laboratory workload affect the schedule. Request a written quotation and reporting time from the laboratory.
Start with the right questions.
Prepare your material details and testing objective before contacting a laboratory.