Metallic Screen Assays Significantly Increase Gold Grades Of High-grade Drill Intercepts At Philadelphia Project
VANCOUVER - Arizona Silver Exploration Inc. reported very positive results from re-assays by the metallic screen procedure on selected drill hole intervals on the Philadelphia epithermal gold project. The highest-grade interval to be re-assayed showed the largest grade increase, 42.2% (51 gpt to 72.5 gpt) gold. A total of 24 samples of both high and low-grade material were re-assayed if they contained visible gold. The samples were all from the spring 2023 reverse circulation (RC”) drilling campaign.
Greg Hahn, VP Exploration, commented, “Re-assaying of samples with coarse gold is a normal industry practice to gauge if grades are being underestimated simply because a standard 30-gram sample for fire assay can miss coarse gold that might not be represented in a 30-gram split.. Re-assaying on 24 samples is considered statistically meaningful as we assayed both higher and lower grade material. For all 24 samples the average grade increased by 25.9%. Going forward we will routinely re-assay high-grade intervals and use the metallic screen technique also on duplicate samples to resolve potential assay discrepancies when our geologist identifies coarse gold in his logging. In due course when Philadelphia advances into the evaluation phase much more re-assaying will be done. In the meantime, I am delighted that our project continues to have positive outcomes as we continue drilling off this deposit.”
Metallic screen assays and duplicate re-assays were run on selected intervals from the spring 2023 RC drilling campaign, where visible gold was identified, in order to assess the potential for coarse gold that is not adequately represented in standard 30-gram fire assay analyses. The results are tabulated herein and show the high-grade intervals clearly have “coarse” gold present in the plus 100-mesh size fraction used in the analyses. This coarse gold fraction tends to be under-represented in a standard 30-gram sample preparation for fire assay. The highest grade samples show the largest amount of “coarse’ gold relative to the lower grade samples, for which the presence of particulate gold does not appear to be an issue. Generally, the results show a dramatic grade increase for samples with initial grades of +4-5 grammes per tonne (“gpt”) gold, although that is not always the case.
The highest grade sample in drill hole PRC23-97, which originally contained a grade of 51 gpt gold, returned a grade of 72.5 gpt gold in metallic screen analyses, a 42% increase in grade. For that sample grades of 65 and 74.8 gpt gold were also returned upon re-assaying the original sample using a larger (50-gram) pulp size. The results of metallic screen analyses and re-assaying using a larger pulp compare very favorably with one another. This suggests re-assaying by the metallic screen procedure of +4 gpt gold internals is recommended. Metallic screen analyses are recommended also when discrepancies exist in standard assay and re-assay sampling.
Overall the metallic screen analysis and re-assaying exercise of the sample selected resulted in a 25.9% increase in average grade of the sample suite. Metallic screen analyses and re-assaying of low-grade samples returns grade discrepancies of generally less than 0.5 gpt gold, and mostly less than 0.1 gpt gold, suggesting coarse gold is not an issue in the lower grade samples submitted for metallic screen analyses.