Black Bear Minerals Confirm Higher Silver Grades at Shafter with Historical Re-Assay Program

Black Bear Minerals (ASX: BKB) has returned further higher-grade silver results from re-analysis of historical drill core at its Shafter silver project in Texas, adding support to an expanded review of legacy drilling across the deposit.

The standout re-assay returned 9.1 metres at 1,043 grams per tonne silver from 116.4m, including 0.6m at 2,990g/t, compared with the original result of 9.1m at 801g/t including 0.6m at 1,284g/t.

That represents a 133% increase in silver grade for the internal interval and a 30% increase in contained silver across the broader intercept, while another re-analysed hole delivered a 5% increase in contained silver.

Multi-element analysis has also identified gold grades up to 0.8g/t and lead grades up to 30% in historical core that was predominantly tested only for silver.

Re-Assays Lift Silver Grades

Black Bear has now generated results from nine drill holes and 233 comparable assay pairs, with broader intercept silver grades increasing in every drill hole re-analysed since it acquired Shafter.

The work compares remaining portions of historical diamond core with modern re-sampling and analytical techniques, including four-acid digestion for silver rather than the two-acid digestion historically used for much of the material.

Preliminary percentile analysis shows a tendency for higher silver grades in the new results across both lower-grade four-acid analyses and over-limit fire assays, although additional data is required before any consistent bias can be demonstrated.

“Shafter continues to surprise on the upside,” chief executive officer Dennis Lindgren said.

With extensive historic core already on site, we have a significant catalyst to progressively build a more complete picture of the Shafter mineralised system as we advance the JORC resource work, Rapid Mine Restart Study, and continue our extensive surface and underground exploration program.”

Polymetallic Picture Building

The re-analysis program is extending beyond silver after recent drilling and surface sampling established that Shafter hosts polymetallic mineralisation including gold, zinc, and lead.

Black Bear is now applying multi-element and gold analysis to historical core across the project to assess the extent and continuity of those commodities, including material both inside and outside the current foreign mineral resource estimate (MRE).

Shafter’s foreign MRE of 17.57 million ounces of silver at 289g/t was prepared under Canadian National Instrument 43-101, meaning it is not currently reported in accordance with the JORC 2012 code.

Metallurgical test work will also be required to assess whether gold, zinc, and lead could contribute as by-products in future technical studies, including the ongoing Rapid Mine Restart Study.

Resource Validation Work

Black Bear has broadened check analysis across additional historical drill programs after twin drilling and historical core re-analysis returned higher-grade or thicker silver mineralisation than corresponding historical data, alongside exploration drilling that confirmed high-grade silver and polymetallic mineralisation.

The program now covers available core across the full MRE footprint, with the company also re-logging and sampling historical material to improve its understanding of other significant commodities at Shafter.

Work is feeding into plans for a maiden JORC MRE and the restart study, while systematic sampling of the historical Presidio Mine workings is intended to assess material left behind when earlier operators selectively mined ore above 500g/t silver.

About 1km of strike within the Presidio Mine remains excluded from the current MRE and has yet to be adequately quantified.