The Barberton Greenstone Belt hosts some of the oldest turbidites in the world.
In the stope
Johan Paul Hunt
This implies that Barberton has more
potential for discovery, but the targets are
expected to be smaller. Barberton would be
ideal for a small- to medium-sized business
to explore, while the expected prizes still to
be found would probably not interest the
majors.
In other words, they would only
be interested in looking for the big
deposits?
Yes, the majors have much higher value
thresholds that need to be met, so their focus
either has to be on the acquisition of Tier
1 mineral assets or to be first-mover in new
terrains and jurisdictions where the possibility
of finding world-class deposits is higher, given
the right geological conditions, of course.
When looking at the residual
potential for the discovery of a
deposit, are there other factors that
can have an influence?
If an exploration company is able to change
the search space, it can have a positive
effect. This is, in effect, the idea of looking
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where others have not or could not look
before. There’s an over-arching principle in
mineral exploration that the largest (and
by extension the most valuable) deposits
are often found early in the exploration
process because they tend to have the
largest geological footprints. If one can be
first mover on a new technology or new
geological model, one can unlock unrealised
potential in old districts. For example, the
introduction of airborne magnetic surveying
in the 1940s permitted the search for
lithological and mineralogical signatures
of large areas and under cover, which was
followed by a flurry of discoveries.
The other ways that a company may
change its search space is either by changing
the conceptual understanding of the
mineralisation or by changing the mining
or beneficiation method. Moving from a
high-grade ore-shoot emphasis to a bulk
tonnage operation, for example, has been
done successfully in other parts of the world,
and this change in mining approach has the
same effect as creating a new search space.
Having said this, some ore deposit types
are more amenable to bulk mining methods
than others.
What has been done in Barberton
historically and are there
opportunities for exploration
companies in the area?
Historically, mining companies working in
the Barberton Greenstone Belt were only
interested in deposits of, let’s say, at least 10g
per tonne or higher. Often sample results
yielding less than 5‒10g per tonne were
ignored. In other words, there is potentially
a lot of metal in the ground. So a shift in
how one thinks about what constitutes an
orebody involving a change in mining method
or application of a different lower-cost
beneficiation technique could unlock this and
hence reduce the cut-off grade. That’s one
of the opportunities in Barberton — look
for lower grade bulk-mineable resources.
Another is looking under the headframes of
historic deposits which were stopped for non-
geological reasons.
Is there land available for new
mining companies to still explore in
the Barberton area?
There is a lot of prospective land in the hands
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