In the stope
John Paul Hunt
talks about
Greenstone potential
The life of one of South
Africa’s oldest mining
regions is far from over,
JP Hunt tells Leon Louw. generative work in Scandinavia and West
Africa with a junior exploration team. After
a stint at the Council for Geoscience where
I focused on prospectivity analysis and the
residual potential of the mineral resources
of South Africa, I joined SRK Exploration
Services about a year ago.
JP, please give us a short summary
of your background in the mining
industry. You have done quite a bit of work
in Barberton, and as I understand,
also in Zimbabwe’s Greenstone
Belt. What method did you apply in
the Greenstone Belt of Barberton?
I studied at the Economic Geology Institute of
Wits University. Most of my research has been
on ore petrology, more specifically assessing
what geological processes are required to make
an economic mineral deposit.
I focused on magmatic nickel initially, but
then pursued other subjects including orogenic
gold, including the Barberton Greenstone
belt, magmatic-hydrothermal systems, such as
porphyry-epithermal copper-gold or iron oxide
copper gold (IOCG), pegmatite-hosted and
vein-hosted mineralisation. I’ve done research
on the Bushveld Igneous Complex, worked for
Norilsk Nickel on several exploration projects
throughout Africa and, following that, I did
[32] MINING MIRROR JULY 2019
I used what is known as the rank statistical
analysis, where the residual potential of a
mineral belt can be estimated by looking at
the size-frequency distributions of the known
deposits. I used this method specifically in
Barberton in 2013 as a way, firstly to motivate
for continued exploration in the belt, but also
to establish an expectation of what the level of
mining maturity of the belt might be and what
might be left to find.
I looked at Zimbabwe in a similar way –
mostly to compare Barberton with a terrain
of comparable geological age and also with a
mining history of similar duration.
Which region of Zimbabwe did you
look at and how does Zimbabwe
compare to the Barberton
Greenstone belts?
I focused on that part of the country where
the cratonic floor rocks are exposed. Both
terrains have very similar geology and they
are almost of the same geological age. The
area of preserved greenstone terrain and the
total known gold endowment in Zimbabwe
are both larger than Barberton terrain by an
order of magnitude, Zimbabwe having more
than 6 000 deposits and prospects versus
Barberton’s 255 recorded workings. They
have both been mined for at least the last 140
years, and so the expectation commonly held
is that these areas have been largely depleted
of their resources.
Analysis of the size-frequency distributions
of both terrains provides some insight into
their respective residual gold potentials.
Zimbabwe can be shown to be far more
mature in terms of its depletion of its
potential for gold deposits of economic
significance than Barberton, that is, having
a greater proportion of its resources already
discovered or exploited.
www.miningmirror.co.za