TORONTO (miningweekly.com) – Canadian explorer Platinum Group Metals (PTM) has defined five large potential mining blocks, each at a scale typical of a standalone South African platinum mine shaft or decline complex, at its Waterberg discovery in the country’s platinum-rich North West province.

TSX- and NYSE MKT-listed PTM on Thursday reported that more than 90% of recent infill drilling on the Waterberg deposit had intersected the T and F layers of mineralisation, extending the deposit both up-dip and at depth.

According to the explorer, confirmation drilling had delineated large-scale F-zone blocks at grades higher than the deposit average, which could be separately modelled and prioritised for mining in an ongoing prefeasibility study. New high-grade T-zone blocks were also emerging at depth.

Further drilling was now under way to offset these new high-grade T-zone intercepts. This had been approved by the Waterberg Joint Venture (JV), which was funded by the Japan Oil, Gas and Metals National Corporation.

"Definition drilling is allowing us to model Waterberg as a series of potential mining areas rather than as one 13 km deposit. Given the scale of known resources and being only 140 m from surface, Waterberg is certainly big and shallow. Waterberg will now be considered a mining district to be prioritised rather than as a single deposit in the ongoing prefeasibility study,” stated president and CEO Michael Jones.

Among the highlights were multiple high-grade Super T-zone intercepts, including 13.91 g/t platinum, palladium and gold (3E) over 11.87 m and multiple Super F-zone intercepts creating targets for shallow resources at less than 300 m vertical from surface.

The 27 new drill holes, comprising 15 500 m of core, plus results from 265 earlier holes representing 249 000 m of core, which were completed for the previous July 2015 resource estimate, outlined five potential mining areas: the T-zone, Super T, Central Super F, Boundary Super F and Northern Super F. Seven holes and 6 000 assays were still pending at this time from the ongoing drill programme, the company advised.

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PTM explained that higher-grade intercepts, combined with earlier higher-grade cuts, created specific blocks that would be considered in prefeasibility mine planning and engineering work. An updated resource calculation was in progress, modelled on 2.5 g/t, 3.5 g/t and 4 g/t platinum, palladium, rhodium and gold (4E) lower cutoff grades for the identified blocks.

The term ‘super’ in the Super T-zone designated an intercept thickness of greater than 6 m at over 5 g/t. In the F-zone, ‘super’ was used for an intercept of more than 10 m. True thickness was about 79% of the reported intercept width.

The company said that it would be logical to consider intercepts at up to 6 m vertical thickness for standard mechanised mining methods. At 6 m to 10 m thick, other methods for mechanised extraction could be considered, while beyond 10 m thick, bulk underground mining methods might be considered.

To put the Super T and Super F intercepts into perspective, PTM explained that a common measure for mine planning comparison in layered deposits was thickness multiplied by grade measured in centimetre grams per tonne (cmg/t). An intercept of 10 m of 3 g/t or an intercept of 6 m of 5 g/t both had 3 000 cmg/t. By comparison, a typical Merensky reef platinum mine would have 1 m of 6 g/t or 600 cmg/t.

Waterberg was newly discovered by PTM and its JV partners in late 2011. The deposit had been studied since its discovery in cooperation with University of the Witwatersrand. Its mineralogy and age date had suggested it was a Bushveld Complex deposit, but in a new set of layers and geological domain. Waterberg was not aligned with the classic South African platinum reefs of the Merensky, upper group two or Platreef.

Effective July 20, the mineral resources at Waterberg on a 100% project basis had risen to an estimated 25.64-million ounces of 3E in the inferred category, in addition to 12.61-million ounces of 3E in the indicated category.

The inferred resource comprised 246-million tonnes grading 3.25 g/t 3E (0.98 g/t platinum, 2.11 g/t palladium, 0.16 g/t gold at a 2.5 g/t cutoff). The indicated resource comprised 121-million tonnes grading 3.24 g/t 3E (0.97 g/t platinum, 2.11 g/t palladium and 0.16 g/t gold).

PTM expected to publish a resource update at the end of the month, and the prefeasibility study was expected to be complete by July. PTM planned to submit its application for a mining right by the end of the year, while bankable feasibility study was in the works for publication in 2017.

PTM’s TSX-listed stock price had more than doubled since the start of the year and on Thursday traded at C$4.25 apiece.