Black Bear Minerals (ASX: BKB) has decided to include all available legacy drill material in its re-analysis of historical core from the Shafter project in Texas, with results to date continuing to confirm promising silver and polymetallic mineralisation.

Shafter lies in Presidio County, West Texas — a silver district with a mining history stretching back to the 1880s — and the deposit was most recently developed as an underground silver mine under previous owners in the early 2010s before operations were curtailed. That legacy of prior development sits behind the company's restart-oriented evaluation approach, which draws on existing surface and underground access at the site.

Chief Executive Officer Dennis Lindgren said Shafter continues to surprise on the upside.

"These latest results include 9.1 metres at 1,043 grams per tonne (g/t) silver with a peak of 2,990 g/t, while also identifying up to 0.8 g/t gold and base metals, largely absent from historic datasets," Mr 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," he said.

The results form part of the re-sampling and check analysis program of historic core being undertaken to validate the 17.5 million ounce (Moz) foreign mineral resource estimate. The company has now received assays for two historic from-surface diamond holes, both completed in 2012.

Under the JORC Code, a foreign estimate is a resource figure prepared under a non-Australasian reporting standard, which an ASX-listed company cannot report as a JORC Mineral Resource until it has completed sufficient verification work — the driver behind Black Bear's re-sampling, check analysis and twin drilling program.

The fresh numbers continue to show an uplift in contained silver for drillhole intercepts compared with the original database — for example, 9.1 metres at 1,043 g/t silver from 116.4 metres, including 0.6 metres at 2,990 g/t silver (re-assay). This represents a +133% increase in silver grade for the internal interval, and a +30% increase in contained silver for the wider intercept, compared with the original intercept.

Notably, results from drillhole S-12-403 returned a considerably higher silver grade than those reported historically, warranting continued investigation into the historic dataset. An uplift of approximately five per cent in silver grade at S-12-420 has helped confirm the tenor of the historical silver mineralisation, while indicating potential for limited grade enhancement through modern analytical methods.

For every drillhole re-analysed since Black Bear Minerals acquired the project, silver grades for the broader intercepts have increased relative to the historically reported intercepts — a pattern that illustrates why re-assaying stored core is a standard early step when legacy datasets are being modernised ahead of a fresh resource estimate.

The company is currently reviewing results from exploration drilling, historic core re-analysis and twin drilling with a view to completing a maiden JORC Mineral Resource Estimate (MRE) and progressing towards completion of the Rapid Mine Restart Study.

In addition to check analysis, Black Bear Minerals is re-logging and sampling available historic core to better understand the distribution of all other significant commodities at the project, with a view to incorporating those results into a future JORC MRE in addition to silver.

BKB shares were up 1.68% at 60.5¢, with a market capitalisation of $90.69 million.

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