The above intercept also contained 9.4m at 20.96% lead, 19.93% zinc, 0.48% copper and 11.6oz/t silver and is part of an on-going 55,000m infill and step-out exploration programme at the Hermosa project in Arizona which will feed into a feasibility study this year.

The company said Taylor would be one of the world's top five zinc equivalent producers when it released an updated PEA and resource nine days ago.

The measured and indicated resource increased 39% to 101 million short tons grading 10.4% zinc equivalent and the updated PEA put capex US$519 million, almost tripled the mine life to 29 years and increased the after-tax NPV by 57% to $2 billion from the 2017 PEA.

"As we continue to grow the resource, it is amazing how many new areas of high-grade mineralisation have been added, especially in the Taylor Deeps Zone," COO Don Taylor said, noting the potential for resource growth and increased grades from the drilling since the September cut-off for the updated PEA.

Arizona's increasing appeal and rampant share price present a quandary for South32 (AU:S32), as Mining Journal columnist Barry FitzGerald points out, with the hopeful would-be owner now looking at almost double the cost to acquire the remaining 85% of Arizona since taking its initial stake last May.

Arizona shares hit a fresh 52-week high yesterday intraday and closed up 6.36% at C$4.85.