Metallic Screen Fire Assay (Coarse / Nuggety Gold)
Specialized screen fire assay eliminating the 'nugget effect' in coarse-gold deposits by screening 1kg of pulverized sample at 106 microns and assaying coarse and fine fractions separately.
Analytical Overview & Methodology
Coarse or ‘nuggety’ gold deposits present significant sampling challenges: standard 30g sample splits can either miss isolated gold grains or capture a single nugget, generating extreme grade variance. Our Metallic Screen Fire Assay (SCR-FA-05) provides the statistical solution recommended by international reporting codes (JORC & NI 43-101).
Screen Assay Mathematical Rigor
A full 1,000g sample is pulverized and screened through a certified 106-micron mesh. Malleable coarse gold flakes cannot pass the screen and are retained in the +106µm fraction, which is fused and cupelled in its entirety to extinction. The homogeneous fine fraction (-106µm) is assayed in duplicate. The laboratory computes the total gold grade using mass-weighted mathematical compositing, delivering indisputable resource estimation data.
| Method Code | SCR-FA-05 |
|---|---|
| Element Coverage | Coarse Gold (>106µm), Fine Gold (<106µm), Total Gold Grade |
| Detection Range | 0.05 – 10,000.0 ppm Au (g/t) |
| Sample Requirement | 1.0 kg to 2.0 kg representative drill core or bulk sample |
| Instrumentation | Ro-Tap Sieve Shaker + Duplicate Fire Assay + Microbalance |
| Standard Turnaround | Standard: 4-6 Working Days |
Laboratory Protocols & Execution Specs
- Sample Size: 1,000g representative crushed sample
- Screening: Precision dry screening at 106 µm (140 mesh) or 75 µm (200 mesh)
- Coarse Fraction (+106µm): Assayed in its entirety by fire assay gravimetric finish
- Fine Fraction (-106µm): Duplicate 30g/50g fire assays with AAS or gravimetric finish
- Final Output: Weighted mathematical composite calculating true representative grade
JORC & NI 43-101 Data Integrity Guarantee
Every batch tested under method SCR-FA-05 includes matrix-matched Certified Reference Materials (CRMs), analytical blanks, and duplicate splits at a minimum 20% insertion rate. Official digital Certificates of Analysis are digitally signed and traceable.