Great Boulder Resources Limited (ASX:GBR) has made a potentially extraordinary discovery of copper-nickel-cobalt mineralisation at Mt Venn, in Western Australia. Extraordinary, because Mt Venn has a remarkable past.

In 1970 the share price of the then-owner, Tasminex NL, rocketed from $3.00 to $96.00. This uplift was based upon a report that nickel mineralisation had been discovered at Mt Venn (it hadn’t). The share price fell back to earth and that effectively coincided with the end of the 1960’s nickel boom.

Ironically, about 2 years later, Tasminex drilled several holes at Mt Venn, with the best result being 30 metres at 0.25% nickel and 1% copper. A great result, but no one cared during the bust. Various other companies have explored the area in subsequent decades but without success.

In 2016 Gold Road Resources Limited (ASX: GOR) drilled a water monitoring bore into a paleochannel at Mt Venn, now part of the Yarmana project. The hole intersected visible sulphides but this was not followed up by GOR as they were in the process of developing the Gruyere gold project. That project is a JV with Goldfields Limited and has resources and reserves of 6.2Moz gold.

GBR entered into a JV with GOR to earn a 75% interest in Mt Venn by spending $5M over 5 years. In March 2017 GBR announced assay results for the water bore. It had intersected 2 lenses of sulphide mineralisation:

6m @ 0.5% copper, 0.1% nickel, 0.02% cobalt, and;

3m @ 0.9% copper, 0.1% nickel, 0.04% cobalt.

These are very good results, particularly given that the hole was not sited to target mineralisation, but to target water in a paleochannel.

Two drill programs have since been completed, with results released in November for the first and February for the second. Better results include:

61m @ 0.5%Cu, 0.15%Ni, 0.05%Co

48m @ 0.75%Cu, 0.3%Ni, 0.07%Co

33m @ 0.5%Cu, 0.1%Ni, 0.05%Co

18m 2 0.7%Cu, 0.2%Ni, 0.05%Co.

The photograph below shows some rather good looking core from Mt Venn.


Image Courtesy Great Boulder Resources Limited

Now there is a school of thought that these grades are low and therefore possibly sub-economic. In my opinion it is far too early to comment on the potential economics of this discovery. There is no resource, and metallurgical testwork has yet to commence. It should also be noted that high tonnage and high tonnes per vertical metre can support a low head grade. Read more on the subject here.

In terms of in situ value, often a questionable measure, the Mt Venn results are positive. At current metal prices, and AUDUSD exchange rate; typical in situ values are in the $110 to $120/t range. Copper and cobalt often have a similar value, each around 35-45% of total value, with the balance being nickel at around 15-20%.


It is very early days in the exploration of Mt Venn/Yamarna, and as such the initial results are excellent. I would be very surprised if we don’t see higher grade results, as exploration progresses and the geology is better understood.

The company does have several other projects in Western Australia, but none has comparable potential to Mt Venn at this stage.

The next phases of work at Mt Venn are metallurgical testwork and geophysics. It is unknown when drilling will restart, presumably once the geophysics are complete and the results interpreted.

Worth watching, particularly the next round of drilling.




My “Worth Watching” series is a brief review of companies that appeal to me. They are in no way a recommendation to buy or sell shares. The reader is advised to do their own research and/or consult with their broker.